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The optical behavior of the square lattices of the hemispherical nanovoids on the surface of the high-refractive-index all-dielectric slabs in the visible range is studied numerically using gallium phosphide as an example. There exist Fano resonances for these metasurfaces for a limited range of thicknesses. The Fano resonances are caused by the interference between the Mie-type scattering resonances of surface pattern elements and the Fabry–Pérot modes of the slabs. The maximum enhancements of the optical Kerr nonlinearity with respect to the bulk material are revealed at the Fano resonances, in particular, for the thinnest nanostructures. Interestingly, no positive correlation between the quality factor and the enhancement of the optical Kerr effect of the metasurface at the Fano resonances is observed. [ABSTRACT FROM AUTHOR]

Gamma-ray-induced luminescence is observed from impurity-doped gallium phosphide (GaP) single crystal wafer at room temperature. The luminescence properties are studied for the undoped and impurity-doped GaP wafer samples. These GaP wafers are irradiated with gamma-rays of 1.17 and 1.33 MeV from a cobalt-60 source. In the gamma-ray irradiation of impurity-doped GaP wafers, a luminescence band peaked at approximately 850 nm is appeared in the spectrum at approximately 750–1000 nm. While for the undoped wafer, the gamma-ray-induced luminescence is not observed, indicating that the origin of the luminescence is attributed to the transition between the impurity levels. The broad emission of the impurity-doped GaP is attributed to the pair emission between the deep O-donor at the P site and the deep Si-acceptor at the P site. The emission intensity does not increase proportionally like the gamma ray induced emission of a GaN single crystal wafer observed in our previous study (Appl. Phys. Lett. 118 (2021) 032106). [ABSTRACT FROM AUTHOR]

Gallium phosphide (GaP) offers unique opportunities for nonlinear and quantum nanophotonics due to its wide optical transparency range, high second-order nonlinear susceptibility, and the possibility to tailor the nonlinear response by a suitable choice of crystal orientation. However, the availability of single crystalline thin films of GaP on low index substrates, as typically required for nonlinear dielectric metasurfaces, is limited. Here we designed and experimentally realized monolithic GaP metasurfaces for enhanced and tailored second harmonic generation (SHG). We fabricated the metasurfaces from bulk (110) GaP wafers using electron-beam lithography and an optimized inductively coupled plasma etching process without a hard mask. SHG measurements showed a high NIR-to-visible conversion efficiency reaching up to 10−5, at the same level as typical values for thin-film-based metasurface designs based on III–V semiconductors. Furthermore, using nonlinear back-focal plane imaging, we showed that a significant fraction of the second harmonic was emitted into the zeroth diffraction order along the optical axis. Our results demonstrate that monolithic GaP metasurfaces are a simple and broadly accessible alternative to corresponding thin film designs for many applications in nonlinear nanophotonics. [ABSTRACT FROM AUTHOR]

Gallium phosphide (GaP) has been increasingly prioritized, fueled by the enormous demands in visible light applications such as biomedical and quantum technologies. GaP has garnered tremendous attention in nanophotonics thanks to its high refractive index, indirect bandgap width of 2.26 eV, lattice perfectly matched with silicon, and omnipotent and competitive nonlinear optical properties. Herein, we review the progress and application of GaP in nanoscale devices over the past two decades. The material properties of bulk GaP are first listed, followed by a summary of the methodologies for fabricating nanoscale devices and related integration techniques. Then, we digest the operational mechanisms across different GaP-based devices on their optical linear responses. Following this, we categorize the GaP nonlinear optical effects into multiple aspects including second-harmonic generation, four-wave mixing, Kerr optical frequency combs, etc. Ultimately, we present a perspective on GaP nanophotonics in the context of coexisting and competing modes of various nonlinear effects. We believe that a comprehensive overview of unique GaP will propel these nanophotonic devices toward a mature state, underpinning foundational understanding and leveraging practical innovations. [ABSTRACT FROM AUTHOR]

High‐power optical transmission (HPOT) technology has emerged as a promising alternative among far‐field wireless power transmission approaches, enabling the transfer of kilowatts of power over kilometer‐scale distances. Its exceptional adaptability allows operation in challenging scenarios where traditional electrical wiring is impractical or unfeasible, thereby opening up a vast array of potential applications previously considered utopian. An important pending assignment in enhancing the performance of laser‐based HPOT systems is achieving efficient photovoltaic conversion of high power densities (≥10 W cm−2). In this sense, there is a pressing need for the advancement of optical photovoltaic converters (OPCs) capable of enduring intense monochromatic irradiances. This work presents the design optimization, manufacturing, and characterization processes of a gallium indium phosphide (GaInP)‐based OPC under varying 637 nm laser power at room temperature. In addition, methods to evaluate the impact of temperature on performance are provided. The findings reveal a maximum efficiency of 53.5% at 10 W cm−2, surpassing literature results for GaInP converters by over 9%abs at those light intensities. Remarkably, this device withstands unmatched irradiances within GaInP OPCs up to 60 W cm−2, maintaining 42.3% efficiency. This study aims to push forward the development of wide‐bandgap power converters with recordbreaking efficiencies paving the way for new applications. [ABSTRACT FROM AUTHOR]

Ytterbium laser sources are state-of-the-art systems that are increasingly replacing Ti:Sapphire lasers in most applications requiring high repetition rate pulse trains. However, extending these laser sources to THz Time-Domain Spectroscopy (THz-TDS) poses several challenges not encountered in conventional, lower-power systems. These challenges include pump rejection, thermal lensing in nonlinear media, and pulse durations exceeding 100 fs, which consequently limit the detection bandwidth in TDS applications. In this article, we describe our design of a THz-TDS beamline that seeks to address these issues. We report on the effectiveness of temperature controlling the Gallium Phosphide (GaP) used to generate the THz radiation and its impact on increasing the generation efficiency and aiding pump rejection while avoiding thermal distortions of the residual pump laser beam. We detail our approach to pump rejection, which can be implemented with off-the-shelf products and minimal customization. Finally, we describe our solution based on a commercial optical parametric amplifier to obtain a temporally compressed probe pulse of 55 fs duration. Our study will prove useful to the increasing number of laboratories seeking to move from the high-energy, low-power THz time-domain spectroscopy systems based on Ti:Sapphire lasers, to medium-energy, high-power systems driven by Yb-doped lasers. [ABSTRACT FROM AUTHOR]

The priority of research efforts over the past two decades has been focused on the effective detection of harmful gases and the development of small, efficient, and reliable nanodimensional sensors. The adsorption of carbon monoxide (CO) gas molecules on zigzag gallium phosphide nanoribbons (zGaPNRs) has been studied using first-principle calculations within the context of Density Functional Theory (DFT). Here, we have evaluated the potential of single-atom thick zGaPNRs in different configurations of nanoribbons for the detection of CO. Many possible configurations of studying the CO molecule adsorption on zGaPNRs have been explored. It is established that the interaction of CO molecules has an impact on the electrical and transport properties of zGaPNRs. The H-GaP-H is the most stable structure with the binding energy ( E b ) of −5.70 eV. The stability is compromised with CO adsorption with CO-GaP-CO being the least stable structure. Pristine structure is semiconducting with the energy band gap ( E G ) of −3.95 eV. The computed sensitivity (S) values are found to be highest for Co-GaPNRs with the S value of 1. 7 7 × 1 0 1 8 and the least sensitive structure is H-GaP-CO with the computed S as 3. 8 4 × 1 0 1 7 . Additionally, it is noted that CO molecules always establish a stable chemical bond with the nanoribbon edges through the C-side. The unique behavior is revealed by the transport characteristics, which demonstrates that when CO adsorption occurs near the Ga edge, the current magnitude is noticeably greater. Our research demonstrates the potential of specific CO adsorption and detection for the development of nanosensors. [ABSTRACT FROM AUTHOR]

Gallium Phosphide (GaP) has recently received considerable attention as a suitable material for building photonic integrated circuits due to its remarkable optical and piezoelectric properties. Usually, GaP is grown epitaxially on III–V substrates to keep its crystallinity and later transferred to silicon wafers for further processing. Here, an alternative promising route for the fabrication of optomechanical (OM) cavities on GaP epitaxially grown on nominally (001)‐oriented Si is introduced by using a two‐step process consisting of a low‐temperature etching of GaP followed by selective etching of the underneath silicon. The low‐temperature (–30 °C) during the dry‐etching of GaP hinders the lateral etching rate, preserving the pattern with a deviation between the design and the pattern in the GaP layer lower than 5%, avoiding the complex process of transferring and bonding a GaP wafer to a silicon‐on‐insulator wafer. To demonstrate the quality and feasibility of the proposed fabrication route, suspended OM cavities are fabricated and experimentally characterized. The cavities exhibit optical quality factors between 103 and 104 at telecom wavelengths, and localized mechanical resonances ≈3.1 GHz with quality factors ≈63 when measured at room temperature. These results suggest a simple and low‐cost way to build GaP‐based photonic devices directly integrated on industry‐standard Si(001) photonic wafers. [ABSTRACT FROM AUTHOR]

Carbon dots (CDs) are promising nanostructures in the field of photonics owing to the ease of fabrication, tunable and efficient emission. Gallium phosphide (GaP) nanowires are known for high surface area, optical density, waveguiding, resonant optical properties but lacking the luminescence due to the indirect bandgap. Here, hybrid photonic structures – GaP nanowires decorated with the CDs are fabricated and studied. Feasible drop‐casting deposition technique allows fabrication of dense vertical structures exhibiting efficient photoluminescence. Deposition of the CDs over the nanowires does not affect their luminescent properties demonstrating tolerance of the approach toward the surface aggregation. Tuning of the emission spectrum is obtained via variation of the excitation wavelength and CDs' synthesis protocol. The structures emitting throughout the visible range are obtained. Analysis of the photoluminescence of an individual structure demonstrates the most intense and fast recombination processes at the ends of a nanowire. It is shown that the luminescence of the CDs' covering a nanowire acting as a Fabry–Perot cavity is enhanced up to a factor of 3 governed by the Purcell effect. The obtained results unveil a path for fabrication of novel photonic devices via decoration of optically dense nanowires with CDs for enhanced and directed broadband emission. [ABSTRACT FROM AUTHOR]

Clean energy hydrogen is a promising substitute for traditional fossil fuels. Hydrogen production via electrocatalytic and photocatalytic water splitting is attracting much attention due to its environmental friendliness. Platinum-based materials are used to promote the kinetic rate for hydrogen evolution reaction (HER). However, the Pt usage is limited by their high price and low content. Much efforts have been put to replace them by non-precious metals. With low melting point and widest liquid temperature range, gallium is easily coupled with other metals or non-metals for constructing composite material for HER, However, systematic research on constructing gallium-based materials for HER is rare and this review could fill in certain gaps of related field. In this work, the preparation method and HER performance of gallium-based materials including gallium alloy, gallium phosphide and their composites, are summarized systematically. This review provides a comprehensive understanding of the structure influences of these gallium-based materials on electrocatalytic and photocatalytic HER performance. Moreover, possible challenges and prospects are also proposed for inspiring people to design excellent gallium-based materials for HER. [ABSTRACT FROM AUTHOR]

In the present work, we have investigated the optical properties of various one-dimensional photonic crystals composed of alternate material layers of silicon dioxide (SiO2) and gallium phosphide (GaP). The choice of GaP material is due to its larger bandgap property with better thermal stability. It belongs to the category of an indirect bandgap semiconductor is commonly used in light-emitting diodes. The optical characteristics of various one-dimensional PCs consisting of different period number N have been investigated by using the transfer matrix approach. The transmittance and absorption characteristics of all structures have been examined. The present study also includes characteristics of the reflectance phase and relative percentage reflectance of all photonic structures. The dependence of the transmission characteristics of all structures on the thickness of SiO2 and GaP material layers as well as on the incident angle corresponding to TE wave only have been also discussed in this work. Unlike two-dimensional and three-dimensional PCs the fabrication of one-dimensional photonic structures is easier. Any of the suitable thin film deposition techniques available at present can be used for the realization of such structures. [ABSTRACT FROM AUTHOR]

This document is a correction notice for an article titled "Investigating the optical properties and electronic structure of gallium phosphide nanotubes doped with arsenic via implementing first-principles calculations" published in the Journal of Molecular Modeling. The correction states that there were errors in Figures 2 and 3 of the original article, as they matched Figure 1 exactly. The corrected versions of the figures are provided in the correction notice. The original article has been corrected. The publisher, Springer Nature, remains neutral regarding jurisdictional claims and institutional affiliations. [Extracted from the article]

In the paper, the influence of growth factors and silicon surface condition on the epitaxial formation of single-domain GaP buffer layers on Si (001) has been studied. A novel two-stage growth technique for the epitaxial building-up of this structure has been put forward and developed. In contrast to using the migration enhanced epitaxy technique, the proposed technology allows one to separate the nucleation and growth stages, to control the doping profile of the GaP buffer layers. The latter is important for further functional applications. The main factors determining the orientation of GaP crystalline lattice when it nucleates on the Si vicinal surface were found. The structural perfection of the grown buffer layers at both stages was proved through careful control by TEM, RHEED, AFM, and HRXRD. These findings have important implications for further functional applications.

This study aimed to investigate the effects of 0.6% hyaluronic acid (HA) gel on the healing process and postoperative pain levels after diode laser-assisted labial frenectomy in pediatric patients. Ninety-six pediatric patients (females, 50 and males, 46) aged 8–14 years were randomly divided into four groups as follows: (1) conventional frenectomy with 0.6% topically administered HA (CFH, n = 24); (2) conventional frenectomy with placebo gel (CFP, n = 24); (3) frenectomy performed by diode laser with 0.6% topically administered HA (DLH, n = 24); and (4) frenectomy performed by diode laser with placebo gel (DLP, n = 24). HA application was continued for 1 week thrice daily after the frenectomy. Visual analog scale forms were collected from patients 1 week after the operation. In addition, the plaque index, gingival index, periodontal probing depth, and keratinized tissue width and thickness were recorded. This process was repeated 1 and 3 months after the first visit. The DLH group revealed significant differences in the probing depth, bleeding on probing, keratinized gingiva width, and attached gingiva width according to dual comparisons of the initial, first, and third-month values (p = 0.010, p = 0.007, p<0.001, and p = 0.001, respectively). Significant differences were observed between the CFP and CFH groups according to the initial and initial third-month values with regard to the bleeding on probing (p=0.019 and p = 0.019, respectively). The attached gingival thickness revealed significant differences between the CFP and CFH groups for the initial and initial-third-month comparisons (p = 0.005 and p = 0.007, respectively). The mean values of the initial and initial-third-month differences were significantly higher in the CFH group than those in the CFP group. HA- and laser-assisted labial frenectomies revealed better outcomes in terms of the probing depth, attached gingiva width, keratinized gingiva width, healing process, and postoperative comfort. [ABSTRACT FROM AUTHOR]

Surface‐enhanced fluorescence of single emitters lies at the heart of single‐molecule DNA sequencers as well as quantum light sources. The state‐of‐the‐art metallic nanoapertures are impaled in a dilemma between enhancing radiative decays and minimizing nonradiative issues such as quenching and resistive heating. Here, lossless gallium phosphide slotted nanodisks are proposed that operate at anapole states by in‐plane excitation, precisely aligning the optical "hot spots" with fluidic focuses of zeptomolar sensing volume. Unlike traditional microscopic configurations, this proposed scheme excited via butt‐coupled in‐plane waveguides not only exhibits averagely 12.4× excitation enhancement growth for a single emitter located in the slot, but also enables precise manipulation of the local density of optical states which gives rise to 13.2× when QY0 = 0.003. Surprisingly, directional collection from the excitation waveguide appears in the optimal approach rather than the collection from a CMOS camera at the bottom. The overall on‐chip fluorescent enhancement is benchmarked with the four dyes' colors, lowering the excitation power to 5.3% of contemporary zero‐mode waveguide (ZMW) devices. [ABSTRACT FROM AUTHOR]

We present an investigation of the electronic, optical, and mechanical characteristics of the nano-structured Gallium Phosphide (GaP) semiconductor. It has been reported that high pressures have an impact on the interesting features. In our investigation, the pseudo-potential method was employed. It has been demonstrated that the phonon frequencies and sound speeds of GaP depend on pressure. The recent study can aid in our understanding of how pressure impacts the properties of nano-structured GaP material and electronics. Our results generally demonstrate good agreement with the experiment. The optoelectronic applications in the high-pressure region could make use of the predicted properties. [ABSTRACT FROM AUTHOR]

Gallium phosphide has long held promise for integrated nonlinear photonics, owing to its high non-linear figure of merit, broad transparency and compatibility with silicon. The recent development of orientation patterning in gallium phosphide has now brought this promise within grasp. Current research efforts are focused on demonstrating and evaluating a variety of second and third-order non-linear processes on the platform, reducing optical losses, and investigating integration with Si. [ABSTRACT FROM AUTHOR]

Ytterbium laser sources are state-of-the-art systems that are increasingly replacing Ti:Sapphire lasers in most applications requiring high repetition rate pulse trains. However, extending these laser sources to THz Time-Domain Spectroscopy (THz-TDS) poses several challenges not encountered in conventional, lower-power systems. These challenges include pump rejection, thermal lensing in nonlinear media, and pulse durations exceeding 100 fs, which consequently limit the detection bandwidth in TDS applications. In this article, we describe our design of a THz-TDS beamline that seeks to address these issues. We report on the effectiveness of temperature controlling the Gallium Phosphide (GaP) used to generate the THz radiation and its impact on increasing the generation efficiency and aiding pump rejection while avoiding thermal distortions of the residual pump laser beam. We detail our approach to pump rejection, which can be implemented with off-the-shelf products and minimal customization. Finally, we describe our solution based on a commercial optical parametric amplifier to obtain a temporally compressed probe pulse of 55 fs duration. Our study will prove useful to the increasing number of laboratories seeking to move from the high-energy, low-power THz time-domain spectroscopy systems based on Ti:Sapphire lasers, to medium-energy, high-power systems driven by Yb-doped lasers.

Palladium nanoparticles were produced by a chemical reagent-free and versatile method called spark ablation with control over particle size and density. These nanoparticles were used as catalytic seed particles for gallium phosphide nanowire growth by metalorganic vapour-phase epitaxy. Controlled growth of GaP nanowires using significantly small Pd nanoparticles between 10 and 40 nm diameter was achieved by varying several growth parameters. Low V/III ratios below 2.0 promote higher Ga incorporation into the Pd nanoparticles. Moderate growth temperatures under 600 °C avoid kinking and undesirable GaP surface growth. In addition, a second batch of palladium nanoparticles of concentration up to 1000 particles μ m−2 was deposited onto the GaP nanowires. Subsequently, three-dimensional nanostructures evolved, with branches growing along the surface of the GaP nanowires. The GaP nanowires revealed a zinc blende structure with multiple twinning and a PdGa phase at the tip of the nanowires and branches. [ABSTRACT FROM AUTHOR]

In the last decades, the metal‐assisted growth approach of semiconductor nanowires (NWs) has shown its potential in controlling crystal properties, such as crystal structure, composition, and morphology. Recently, literature reports have shown successful semiconductor NW growth with multiphase seed particles under growth conditions. Exploring alternative metal seeds and the mechanisms for growing semiconductor NWs is an exciting research field aiming to improve the control over the crystal growth process. Herein, the gallium phosphide (GaP) NW growth using Cu as seed particles inside an environmental transmission electron microscope is studied. In particular, the transformations of the Cu‐rich seed particles during the nucleation and growth of GaP NWs are observed. The supply of a relatively high amount of Ga atoms by the precursor mixture led to a solid Cu‐rich seed particle core covered by a liquid phase. Different growth dynamics within the two‐phase seed particle resulted in local competition in NW growth. As a result, the GaP NW kinked into another growth direction by forming a new interface at the NW growth front. The generated results enable insights into fundamental processes occurring in the seed particle during growth, creating leverage points for controlling the NW morphology. [ABSTRACT FROM AUTHOR]

Investigations of atomic-layer deposition of GaP layers on Si substrates with different orientations and with different preliminary surface treatment have been carried out. The deposition of GaP was carried out by the method of plasma enhanced atomic-layer deposition using in situ treatment in argon plasma. It was shown that at the initial stage of the growth of GaP layers on precisely oriented (100) Si substrates and with misorientation, two-dimensional growth occurs both after chemical and plasma surface treatment. Upon growth on (111) substrates, after plasma treatment of the surface, a transition to three-dimensional growth is observed, at which the size of islands reaches 30–40 nm. The smallest root-mean-square roughness of the surface of the growing GaP layers (<0.1 nm) was achieved for (100) substrates with a misorientation of 4°. The GaP layers grown on (100) substrates had a roughness of ~0.1 nm, and on substrates with the (111) orientation—0.12 nm. It was found that the surface treatment of Si substrates with the (100) orientation in hydrogen plasma leads to a slight increase in the surface roughness of growing GaP layers (0.12–0.14 nm), which is associated with the effect of inhomogeneous etching of silicon in hydrogen plasma. When treating the (100) silicon surface in argon plasma, the surface roughness does not change significantly in comparison with the chemical surface treatment. On the surface of substrates with preliminary deposition of an epitaxial Si layer with a thickness of 4 nm, the morphology of GaP layers is the same as in the case of using hydrogen plasma. [ABSTRACT FROM AUTHOR]

Gallium phosphide (GaP) is a promising material for nanophotonics, given its large refractive index and a transparency over most of the visible spectrum. However, since easy phase‐matching is not possible with bulk GaP, a comprehensive study of its nonlinear optical properties for harmonic generation, especially when grown as thin films, is still missing. Here, second harmonic generation is studied from epitaxially grown GaP thin films, demonstrating that the absolute conversion efficiencies are comparable to a bulk wafer over the pump wavelength range from 1060 to 1370 nm. Furthermore, the results are compared to nonlinear simulations, and the second order nonlinear susceptibility is extracted, showing a similar dispersion and magnitude to that of the bulk material. Furthermore, the third order nonlinear susceptibility of amorphous GaP thin films is extracted from third harmonic generation to be more than one order of magnitude larger than that of the crystalline material, and generation of up to the fifth harmonic is reported. The results show the potential of crystalline and amorphous thin films for nonlinear optics with nanoantennas and metasurfaces, particularly in the visible to near infrared part of the spectrum. [ABSTRACT FROM AUTHOR]

The thermovoltaic effect, which is the occurrence of an electromotive force (EMF) in a substance during its uniform heating, is a promising phenomenon for the development of effective converters of solar thermal energy into electrical energy. However, the problem of suitable materials and design of the thermovoltaic element remains open. Therefore, this work is devoted to the study of the thermovoltaic effect in n‑GaSb, n-GaAs, and n-GaP binary compounds. The current–voltage characteristic (I–V curve) of the structures Ni–Ag–GaSb–Ag–Ni, Ni–Ag–GaAs–Ag–Ni, Ni–Ag–Sn–GaP–Sn–Ag–Ni, Ni–Ag–Si–Ag–Ni, and Au–Ni–Ag–Au are investigated in the temperature range of 300–500 K. As the temperature increased, shifts in the I–V curves of semiconductor structures are observed towards increasing voltage and current, which indicates the appearance of EMF and current during uniform heating. At 500 K, the points of intersection of the I–V curves with the voltage axis are 10.6 mV for GaP, 6.3 mV for GaSb, 5.3 mV for GaAs, and 0.9 mV for Si, as well as with the current axis, respectively 3.8 μA cm–2 for GaP, 480 μA cm–2 for GaSb, 184 μA cm–2 for GaAs, and 2.7 μA cm–2 for Si. Uniform heating of the structures under consideration in the dark leads to the occurrence of EMF and current in them. The thermally stimulated EMF of the GaSb and GaAs compounds was almost the same (0.2 mV) and an order of magnitude lower than the EMF of the GaP compound (2.5 mV) at 428 K. [ABSTRACT FROM AUTHOR]

In this paper, the optical properties of GaP in different phases have been investigated. The calculations were performed by using pseudopotential in the framework of density functional theory and using the PWscf code. The pseudopotentials applied here are generated using norm-conserving conditions within GGA for the exchange-correlation function. The optical properties of the Zincblend and Cinnabar phases reveal the conformity between the band structure and the imaginary part of the dielectric function, and the band gap and optical gap are almost equal. The refractive index obtained from the real part of the dielectric function in Zincblend is 3.306 and in the Cinnabar phase is 4.235 and 3.808 in the x and z directions, respectively.

A model used to simulate and optimize the performance of nanowire-based betavoltaic generators is developed. The optimum nanowire array geometry is established for devices made of silicon, gallium arsenide, and gallium phosphide for both nickel-63 and tritium sources by computing the energy capture efficiency for each case. The captured power for nanowire devices is shown to be drastically greater compared to planar betavoltaic generators with maximum improvement factors of approximately 7, 3, 5, and 9 for devices utilizing radioisotope sources of nickel-63, nickel citrate, tritium, and tritiated butyl, respectively. In addition, nanowire devices do not suffer from self-shielding effects, a large limitation in conventional, planar betavoltaics. By coupling the spatial distribution of electron–hole pair generation rate calculated from Monte Carlo simulations and a semiconductor charge-transport model, the diode design is optimized for the maximum power output. The top performing devices, utilizing a tritium source, exhibited an output power of approximately 4, 6, and 2 μW cm−2 for silicon, gallium arsenide, and gallium phosphide, respectively. Overall device efficiencies were found to range from 4% to 10%, surpassing several betavoltaic devices reported in the literature. It was also found that, contrary to the traditional betavoltaic design, semiconductors with higher bandgaps do not necessarily result in the best device performance due to additional material parameters, such as surface recombination velocity. Potential improvements for nanowire-based betavoltaic generators are suggested for additional investigation. [ABSTRACT FROM AUTHOR]

In the last decades, the metal‐assisted growth approach of semiconductor nanowires (NWs) has shown its potential in controlling crystal properties, such as crystal structure, composition, and morphology. Recently, literature reports have shown successful semiconductor NW growth with multiphase seed particles under growth conditions. Exploring alternative metal seeds and the mechanisms for growing semiconductor NWs is an exciting research field aiming to improve the control over the crystal growth process. Herein, the gallium phosphide (GaP) NW growth using Cu as seed particles inside an environmental transmission electron microscope is studied. In particular, the transformations of the Cu‐rich seed particles during the nucleation and growth of GaP NWs are observed. The supply of a relatively high amount of Ga atoms by the precursor mixture led to a solid Cu‐rich seed particle core covered by a liquid phase. Different growth dynamics within the two‐phase seed particle resulted in local competition in NW growth. As a result, the GaP NW kinked into another growth direction by forming a new interface at the NW growth front. The generated results enable insights into fundamental processes occurring in the seed particle during growth, creating leverage points for controlling the NW morphology.

Orientation-patterned gallium phosphide (OP-GaP) and orientation-patterned gallium antimonide (OP-GaSb) have demonstrated excellent potential for broadband second harmonic generation (SHG), with a wide range of fundamental wavelengths and temperature tunability, making them promising candidates for use in various applications. In this paper, an analytical demonstration of forward and backward broadband SHG is presented, delivering the fundamental wavelengths in 0.7–12.5 and 2.4–9.8 µm, respectively, through the utilization of OP-GaP and OP-GaSb with quasi-phase-matching (QPM). The temperature tuning ranges for OP-GaP and OP-GaSb are −195–176 and −192–126 °C, respectively. OP-GaP and OP-GaSb can obtain forward broadband QPM SHG when the conditions of QPM and group-velocity matching (GVM) are satisfied simultaneously. The bandwidths of OP-GaP and OP-GaSb with lengths of 10 mm are found to be 776 and 484 nm, respectively, in the forward GVM fundamental wavelength for forward broadband SHG at 25 °C. The bandwidths for backward broadband SHG in the forward GVM fundamental wavelength are also calculated, but the results showed that OP-GaP and OP-GaSb can only achieve forward broadband QPM SHG. Variations of the GVM fundamental wavelength have also been demonstrated as a function of temperature. [ABSTRACT FROM AUTHOR]

Colloidal nanoparticles of gallium phosphide (GaP) with moderately high refractive index (n > 3) and a small extinction coefficient in the visible range are developed using a combination of mechanical milling and a pulsed laser melting process in solution. The combined process yields GaP nanoparticles with an almost spherical shape and the smooth surface. The single particle scattering spectroscopy reveals that smoothening of the surface by the pulsed laser melting process is crucial for achieving distinctive Mie resonances of the dipolar and higher‐order modes in the visible range. The near‐field profile at the Mie resonances studied by electron energy loss spectroscopy in a scanning transmission electron microscope confirms the existence of the magnetic dipole mode. Finally, the Purcell enhancement of fluorescence of molecules on the surface due to the Mie resonances is demonstrated. [ABSTRACT FROM AUTHOR]

[Display omitted] • 4-terminal III-V//c-Si multijunction device with a TOPCon bottom cell. • Wide-gap poly-SiO x as back surface field for TOPCon device. • Bifacial illumination of the 4-terminal device is examined. • Over 34% of cell efficiency with extra 0.25-sun illumination at the back. We propose a structural innovation for a four-terminal III-V//crystalline silicon (c-Si) multijunction (MJ) device under bifacial illumination. The top cell is a double-junction gallium indium phosphide (GaInP)/gallium arsenide (GaAs) cell structure, and the bottom cell is a tunnel oxide passivating contact (TOPCon) structure with a boron-diffusion emitter and a wide-gap polysilicon oxide (poly-SiO x) passivating rear contact. To maximise the albedo-reflectance light transmitted into the c-Si absorber, the wide-gap poly-SiO x passivating contact is intended to replace the conventional narrow-gap polysilicon (poly-Si) passivating contact at the rear of the TOPCon. With an extra 0.25-sun illuminated light at the back, the bottom cell's conversion performance improves by 14.5%. When compared to mono-illumination, bifacial illumination increases the overall efficiency of the MJ device by 2.67%. The design shows great potential for enhancing further the conversion performance of the bifacial GaInP/GaAs//TOPCon MJ devices using the wide-gap poly-SiO x passivating rear contacts. [ABSTRACT FROM AUTHOR]

This paper presents preliminary results of a high speed 1550 nm indium gallium arsenide (InGaAs)-based mesa-type modified uni-traveling carrier photodiode (M-UTC-PD) structure. Conventional UTC-PD refers to P-I-N type photodiodes which selectively use electrons as active carriers. Photons absorbed in the relatively thin P-type absorber create minority carriers which are field accelerated toward a depleted collector thereby establishing high velocity ballistic transport, making these structures applicable for high speed applications. The M-UTC-PD structure presented uses spatially tailored P-type absorber regions to limit minority carrier generation both in the lateral and axial dimensions. Utilizing an otherwise conventional UTC-PD epitaxial structure where the top P-type layers are undoped, the spatially tailored P-type regions are defined by closed ampoule Zinc diffusion techniques. The M-UTC-PD structure presented utilizes a series of nested p-doped rings within a mesa structure to limit dark current and reduce overall capacitance to improve high speed operation. Two photodiode structures will be investigated for this research project, a conventional UTC-PD structure and a modified structure, utilizing similar device designs, epitaxial designs and fabrication processes. The conventional structure will be utilized for fabrication process development, verification of epi quality and development of rapid prototyping approach toward chip-based testing and subsequent high speed RF testing procedures. Conventional UTC-PD device results will be used as a comparison to quantify the performance of the M-UTC-PD structure utilizing Zn-doped defined p-type absorber regions. Results are given for chip tests of UTC-PD chips verifying epitaxial quality and fabrication process, subsequent testing of packaged devices and RF analysis remains. Process development of the Zn-doped devices is underway, once completed, these devices will be compared to the base design to quantify performance enhancement associated with the modified design. [ABSTRACT FROM AUTHOR]

Direct measurements of the electric field of light enable new observations of light–matter interactions. In the near‐infrared and visible spectral ranges, this typically relies on techniques that exploit nonlinearities in gases or solids, which limits their sensitivity. Here, a method for the detection of broadband near‐infrared fields spanning more than one octave from 110 to 220 THz based on linear absorption in a semiconductor is demonstrated. This technique, which avoids complex vacuum setups and works under ambient conditions, employs linear photoconductive sampling (LPS) in gallium phosphide. Simulations reveal that the response function of LPS is concerned with the intensity envelope of the gate field, in contrast to electro‐optic sampling, relaxing the stringent temporal requirements on the gate pulse. [ABSTRACT FROM AUTHOR]

The article presents the results of a simulation of changes in gallium phosphide (GaP) resistivity under the influence of lighting. The adopted model of the defect structure is presented along with the defect parameters. Initial conditions created on the basis of a tested material sample, labeled GaP-1, made of monocrystals of semi-insulating gallium phosphide (SI GaP), are presented. The simulation methodology and the created model of the kinetics equations are described. As a result of the simulation, the values of the photocurrent and the electron-hole pair generation coefficient G were assigned to data obtained experimentally depending on the carrier lifetime coefficient τ. Changes in resistivity and concentration of electrons and holes in the bands for gallium phosphide with a structure consisting of five defects are presented. The proposed simulation method can be used to calculate switch-on and -off times and photocurrent values for the semiconductor materials used to construct PCSS (photoconductive semiconductor switches) and other electronic devices. [ABSTRACT FROM AUTHOR]

Orientation-patterned gallium phosphide (OP-GaP) has been grown heteroepitaxially on OP gallium arsenide (GaAs) templates using hydride vapor phase epitaxy (HVPE). The effect of OP-GaAs template fabrication methods of epitaxial-inversion and wafer bonding on the heteroepitaxial OP-GaP growth has been investigated. OP-GaP layers with a growth rate of up to 35 µm/h and excellent domain fidelity were obtained. The growth rate and the domain fidelity have been revealed/studied by scanning electron microscope (SEM). In addition, we demonstrate that the crystalline quality of the individual domains, namely, the substrate-oriented domains (ODs) and the inverted domains (IDs), can be investigated by high-resolution x-ray diffraction reciprocal space mapping (HRXRDRSM), which can also indicate the domain fidelity. Attempts to increase the growth rate and improve the domain fidelity by increasing the III and V group precursors resulted in either an increase in the growth rate in the OP-GaP layers grown on epitaxial inversion OP-GaAs template at the expense of the domain crystalline quality and fidelity or an improvement in the crystalline quality of the domains at the expense of the growth rate in the OP-GaP layers grown on wafer-bonded OP-GaAs templates. In the case of OP-GaP grown on OP-GaAs templates prepared by epitaxial inversion, the crystalline quality of the ODs is better than that of the IDs, but it shows that the quality of the inverted layer in the template influences the quality and fidelity of the grown domains. To the authors' knowledge, exploitation of HRXRDRSM studies on OP-GaP to establish the crystalline quality of its individual domains (ODs and IDs) is the first of its kind. OP-ZnSe grown on OP-GaAs templates has also been included in this study to further emphasize the potential of this method. We propose from this study that once the growth rate is optimized from SEM studies, HRXRDRSM analysis alone can be used to assess the structural quality and to infer the domain fidelity of the OP structures. [ABSTRACT FROM AUTHOR]

The geometry of a gallium phosphide nanowire (NW) array has been optimized for maximum current generation in a betavoltaic (BV) device. The energy capture efficiency for various device geometries with different radioisotope source compounds was calculated in GEANT4. A validation of GEANT4 for BV device simulation was performed by comparing a model output with the available bulk semiconductor BV performance data, followed by predictions of the performance of NW-based devices. The pitch and the diameter of the NWs were found to have the most significant impact on the β-generated current density, with the optimum diameter-to-pitch ratios ranging from 0.55 to 0.8, depending on the source. The energy capture efficiency improved when low energy beta (β) emitters were used. For devices utilizing 63Ni source compounds, the β-generated current densities approached 0.95 μA cm−2, representing an improvement by a factor as high as 5.8 compared to planar devices. In the case of 3H source compounds, the generated current density was 3.05 μA cm−2, a factor of 15.5 larger than comparable planar devices. However, NW devices utilizing sources with a higher decay energy, such as 147Pm, did not demonstrate any improvements over planar geometries. Using the results for optimum NW geometries, NW-based or other nanostructured devices could be made to surpass the present commercial BV batteries. [ABSTRACT FROM AUTHOR]

GaP/Si(001) virtual substrates are highly interesting for solar cells and optoelectronic device applications. While antiphase disorder at the resulting surface of the virtual substrate—after a few tens of nm GaP—can be suppressed, the structural and electronic properties of the actual GaP-to-Si interface and of the antiphase domains within the GaP are still of high importance. Here, we compare scanning tunneling microscopy data of the prepared Si(001) 2 ° off-oriented substrate with cross-sectional scanning tunneling microscopy data (XSTM) taken after GaP 0.98 N 0.02 /GaP growth. Besides regions where an intermixing of Si with GaP cannot be excluded, we also observe sections with a quite abrupt appearance. In addition, basic knowledge for use of contrast mechanisms occurring in XSTM experiments at antiphase boundaries will be established in order to understand their atomic structure. Thereby, we present a structural model for an entire antiphase domain cross section, including antiphase boundary facet-type determination. Furthermore, we find indications that the majority of the antiphase boundaries within this sample exhibit an equal number of so-called wrong bonds and that XSTM will allow to directly determine the electronic impact of the antiphase boundaries on its surroundings in the future. [ABSTRACT FROM AUTHOR]

The best solar conversion efficiencies have been reached thanks to multijunction solar based on III-V semiconductors on GaAs or Ge substrates. While displaying high conversion efficiencies, these solar cells suffer from the high cost of such substrates. To benefit from both the low cost and technological maturity of silicon cells, III-V tandem cells on silicon seem a good compromise to overpass the theoretical efficiency limit of the Si single cells. To study the GaP/Si interface effect on the solar cell characteristic, a GaP n-i-p solar cell has been grown on silicon substrate. Two types of electrical contacts configurations have been processed: a top-top configuration in which the current does not see the GaP/Si interface and the top-bottom configuration where the electric current crosses the interface. A comparison of dark I-V, I-V under solar illumination, and EQE measurements on both configurations is performed. The top-bottom contacts configuration shows an EQE a little bit lower than the top-top contact one, likely due to lower carrier diffusion length or recombination at the lower interface. However, the result on the EQE of the top-bottom configuration is encouraging for the future development of the GaP-based/Si tandem solar cells, and any other tandem cell on silicon using GaP as an intermediate selective contact. [ABSTRACT FROM AUTHOR]

Mechanical resonators can act as excellent intermediaries to interface single photons in the microwave and optical domains due to their high quality factors. Nevertheless, the optical pump required to overcome the large energy difference between the frequencies can add significant noise to the transduced signal. Here we exploit the remarkable properties of thin-film gallium phosphide to demonstrate bi-directional on-chip conversion between microwave and optical frequencies, realized by piezoelectric actuation of a Gigahertz-frequency optomechanical resonator. The large optomechanical coupling and the suppression of two-photon absorption in the material allows us to operate the device at optomechanical cooperativities greatly exceeding one. Alternatively, when using a pulsed upconversion pump, we demonstrate that we induce less than one thermal noise phonon. We include a high-impedance on-chip matching resonator to mediate the mechanical load with the 50-Ω source. Our results establish gallium phosphide as a versatile platform for ultra-low-noise conversion of photons between microwave and optical frequencies. Coherently interfacing microwave and optical radiation at the single photon level is an outstanding challenge in quantum technologies. Here, the authors show bi-directional on-chip conversion between MW and optical frequencies exploiting piezoelectric actuation of a gallium phosphide optomechanical resonator. [ABSTRACT FROM AUTHOR]

Using first-principle calculations, we have studied the structural and electronic properties of the Gallium Phosphide (GaP) nanoribbon doped with rare earth (RE) metal elements. The substitution of Ga and P atoms with RE leads to the structural deformation in zigzag GaP nanoribbon. For every nanostructure under study, the binding energy (E b), density of states (DOS), and electronic band structures have been computed. The bare and pristine undoped GaP show non-magnetic behavior. The bare z-GaPNR shows metallic nature while the pristine z-GaPNR exhibits band gap of 2.44 eV with indirect characteristics. With Samarium (Sm) and Gadolinium (Gd) doping in z-GaPNR, a transformation of the semiconducting nature of z-GaPNRs turns to half metallic one. The transport properties show that half-metal ferromagnetic behavior with 92%–98% spin polarization at the Fermi level is produced by RE (Gd, Sm) co-doped z-GaPNRs. The synergistic effect of the Gd and Sm impurities are seen to diminish energy band gaps. Conversely, we have the energy band gap in spin down energy levels results in semiconducting behavior, whereas in the spin up energy state, metallic behavior is observed. This could be caused by the 4 f -states of the Sm and Gd dopants. Therefore, this work presents half-metallic (HM) properties for RE-doped z-GaPNRs. Our study depicts that the electrical, spin, and transport properties of z-GaPNRs could be altered magnificently by co-doping of Gd and Sm rare earth metals. Additionally, the current findings can be used to create a workable method of absolute fermi level shifting for spin energy levels, which is required for applications involving spintronic devices, spin filters, as well as for z-GaPNRs' electrical characteristics modifications. • The impact of double RE (Gd, Sm) co-doped z-GaPNRs on their magnetic properties. • RE co-doping results in half-metallic behavior with 92%–98% spin polarization. • RE (Gd, Sm) co-doping in z-GaPNRs reduces energy band gaps. • There is finite energy band gap in spin down and metallic behavior in spin up states. [ABSTRACT FROM AUTHOR]

Beam splitters are vital components in several optical systems. It is highly desirable, and compact beam splitters with ultra-broadband performances, high efficiencies, and large split angles are still being sought. In this paper, we demonstrate and numerically investigate an ultra-broadband and highly efficient optical beam splitter based on a quasi-continuous metasurface. The proposed design is constructed of quasi-continuous triangle-shaped gallium phosphide nanoantennas on a silica substrate. The simple structure can achieve a conversion efficiency and an anomalous transmission intensity above 90% and 0.8 covering the wavelength range of 1537–1826 nm, respectively. The maximum beam split angle in the operating bandwidth reaches 131.84° at the wavelength of 1826 nm. Particularly, the operating bandwidth is still as high as 125 nm with the anomalous transmission intensity above 0.92 and the conversion efficiency exceeding 99%. Moreover, the results show that the performance of the metasurface-based optical beam splitter can be further enhanced by optimizing structural parameters. We also demonstrate the adjustability of the beam splitter by adding refractive index (RI) materials on the surface of the device. The results show that the incident plane wave can be divided into three beams with intensity adjustability. The presented metasurface is very promising in the fields of multiplexers, interferometers, and optical communications, owing to its advantages of ultra-broadband, highly efficient, and large split angle simultaneously. [ABSTRACT FROM AUTHOR]

Using a laser-heated diamond anvil cell, a powdered sample of gallium phosphide was compressed to 17.5 GPa and heated up to 1400 K. The material obtained was characterized at room temperature using synchrotron x-ray diffraction. Experimental results were compared with first-principles calculations. The polymorph observed assumes the simple cubic structure (sc16) initially reported for GaAs at high pressures. Microdiffraction mapping showed variable grain sizes of the synthesized phase, with the largest grains located in the middle of the heated spot. Structural refinements were performed on selected grains. The structure predicted based on first-principles calculations is in close agreement with the experiments. The two Ga–P bonds show similar lengths in sc16-GaP; however, the bond angles differ, resulting in a distorted tetrahedral coordination geometry. [ABSTRACT FROM AUTHOR]

Orthorhombic MnP nanoclusters are formed in GaP epitaxial films grown by metalorganic vapor phase epitaxy on GaP(001) substrates, which are labeled as GaP:MnP/GaP(001). Polycrystalline MnP films have also been grown from the vapor phase on GaP substrates and are labeled as (p-c)MnP/GaP(001). Both GaP:MnP/GaP(001) epilayers and (p-c)MnP/GaP (001) films show a very rich texture, which has been previously characterized by three dimensional x-ray diffraction reciprocal space maps combined with transmission electron microscopy measurements. Heterostructures (HSs) containing multiple layers of (p-c)MnP/GaP and of GaP:MnP/GaP have been designed and grown with the same process. These HSs add new elements to our understanding of the growth mechanisms involved in these complex systems. In particular, it is shown that Mn diffusion during growth is strongly enhanced leading to a picture of MnP cluster coalescence, which explains some of their properties, such as the variation of their spatial distribution within the GaP matrix with the epilayer thickness. We report an Mn atomic diffusion coefficient of (1.5 ± 0.2) × 10−15 cm2/s in these films at 650 °C. The data are compatible with the superdiffusion of Mn, where the square of the diffusion length as a function of time (t) obeys λ D 2 ∝ t 1 + α with an estimated value of α ≈ 0.52. [ABSTRACT FROM AUTHOR]

We present a method for the in situ determination of Young's modulus of a nanomechanical string resonator subjected to tensile stress. It relies on measuring a large number of harmonic eigenmodes and allows us to access Young's modulus even for the case of a stress-dominated frequency response. We use the proposed framework to obtain Young's modulus of four different wafer materials, comprising three different material platforms amorphous silicon nitride, crystalline silicon carbide, and crystalline indium gallium phosphide. The resulting values are compared with theoretical and literature values where available, revealing the need to measure Young's modulus on the sample material under investigation for precise device characterization. [ABSTRACT FROM AUTHOR]

In this study, Pre-diagnosis of degraded aluminum indium gallium phosphide (AlInGaP) light-emitting diodes (LEDs) that were soaked in liquid nitrogen (LN2) was performed. To visualize the early deterioration of LED emission, a combination of material, electrical, optical, and computer-aided machine-vision analysis of LED failure spots on the surface was examined. Results indicate that several small failure spots, which can be identified by the MATLAB processed emission images and surface roughness variation, can be found. Furthermore, LN2 soaking induced some local damages inside the device that penetrate the multiple-quantum well. The decrease of current and luminescence intensity also reflects the gradual degradation of the device after being soaked in LN2. This integrated analysis and Pre-diagnosis of the degraded device provided early screening of LED failure spots and real-time inspection during operations. [ABSTRACT FROM AUTHOR]

Gallium phosphide (GaP) is an important optical material due to its visible wavelength band gap and high refractive index. However, the bandgap of the thermodynamically stable zinc blende GaP is indirect, but wurtzite (WZ) structure GaP is direct bandgap. In this work, we demonstrate high-quality and dense GaP vertical nanopillar (NP) array directly on Si (111) substrates through selective area epitaxy (SAE) by MOCVD for the first time, through systemic studies of the effect of TMGa flow rate, growth temperature, and V/III ratio. Uniform GaP NPs are grown over a patterned $400\,\,\mu \text{m}\,\,\times 400\,\,\mu \text{m}$ area with 97.5% yield. Arrays of GaP vertical p-i-n NP diodes are demonstrated with a ideality factor and rectification ratio of 3.7 and 103, respectively. With the high yield of hexagonal structure and electrically proven device quality of GaP NPs through this growth method, this work represents a significant step in achieving GaP NP based optoelectronic devices, such as micro-LEDs emitting in the green wavelength range. [ABSTRACT FROM AUTHOR]

We report a semiconductor contact grating terahertz source design based on a rectangular profile for phase-matched terahertz generation in the long infrared pump wavelength range. The calculations show that the best diffraction efficiency can be achieved by a filling factor significantly smaller than 50%. Furthermore, the possibility of diffraction efficiency enhancement was investigated by applying three different antireflective coating structures. Numerical simulations have indicated that at 2.06 μ m and 3.0 μm pump wavelength, diffraction efficiencies greater than 91% and 89% can be achieved by adding an appropriate antireflective coating to the GaP and GaAs contact grating structure, respectively. In addition, numerical simulations were performed to investigate the influence of wall angles on diffraction efficiency. The results reveal that the wall angle does not significantly affect the diffraction efficiency: while keeping the wall angle deviation from the vertical below 25 degrees, the efficiency drop remains below 5% for otherwise optimal grating parameters. [ABSTRACT FROM AUTHOR]

Electrical properties of semiconductor materials depend on their defect structure. Point defects, impurities or admixture contained in a semiconductor material, strongly affect its properties and determine the performance parameters of devices made on its basis. The results of the currently used methods of examining the defect structure of semiconductor material are imprecise due to solution of ill-posed equations. These methods do not allow for determination of concentration of the defect centers examined. Improving the resolution of the obtained parameters of defect centers, determining their concentration and studying changes in the resistivity of semi-insulating materials can be carried out, among others, by modelling changes in the concentration of carriers in the conduction and valence bands. This method allows to determine how charge compensation in the material affects the changes in its resistivity. Calculations based on the Fermi-Dirac statistics can complement the experiment and serve as a prediction tool for identifying and characterizing defect centers. Using the material models (GaP, 4H–SiC) presented in the article, it is possible to calculate their resistivity for various concentrations of defect centers in the temperature range assumed by the experimenter. The models of semi-insulating materials presented in the article were built on the basis of results of testing parameters of defect centers with high-resolution photoinduced transient spectroscopy (HRPITS). The current research will allow the use of modelling to determine optimal parameters of semi-insulating semiconductor materials for use in photoconductive semiconductor switches (PCSS).

Gallium phosphide is a low-loss, high-refractive-index semiconductor considered as a promising material for active and passive components in modern nanophotonics. In this work, we show that nanoscale epitaxial layers of GaP with high optical quality can be formed directly on the transparent sapphire wafers despite the symmetry and lattice constant mismatch. This is achieved using a two-step growth technique through the framework of a domain matching epitaxy mechanism. Direct molecular beam epitaxial growth enables the control of material properties and layer thickness with subnanometer precision and allows us to obtain (111)-oriented epitaxial layers of GaP on high-optical-contrast sapphire wafers without the use of postgrowth layer transfer techniques. The influence of growth conditions on the structural quality of GaP-on-sapphire is revealed using Raman spectroscopy and X-ray diffraction reciprocal space mapping. We study the impact of the growth procedure employing a low-temperature seeding layer on the GaP layer morphology and structural quality. Spectroscopic ellipsometry measurements confirm that both the refractive index and the absorption coefficient of the epitaxial GaP layers are close to those of bulk GaP crystals. We also discuss how the GaP layer morphology and structural quality affect its optical density, drawing special attention to the mechanisms of optical losses. Finally, by nanostructuring the grown layer, we fabricate single GaP nanoantennas and confirm their highly resonant optical response in the visible spectral range, thus confirming the feasibility of the reported technology for various nanophotonic applications. [ABSTRACT FROM AUTHOR]