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Herein, the structural properties and chemical composition of Ge samples implanted with tellurium at cryogenic temperatures are analyzed, focusing on the role of the native oxide. For germanium, cryogenic‐temperature implantation is a requirement to achieve hyperdoped impurity concentrations while simultaneously preventing surface porosity. In this work, the critical role of the thin native germanium oxide is demonstrated when performing ion implantations at temperatures close to the liquid nitrogen temperature. The structural and chemical composition of tellurium‐implanted samples as a function of the implanted dose from 5 × 1014 to 5 × 1015 cm−2 is analyzed. After a laser melting process, the incorporated oxygen is diffused to the surface forming again a GeOx layer which retains a large fraction of the total implanted dose. These detrimental effects can be eliminated by a selective etching of the native oxide layer prior to the ion implantation process. These effects have been also observed when implanting on Si substrates. This work identifies key aspects for conducting implantations at cryogenic temperatures, that are otherwise negligible for ion implanting at room temperature. [ABSTRACT FROM AUTHOR]

Based on the ultrafast and extremely strong interaction between laser pulses and materials, ultrafast laser irradiation can break the solid solubility constraints and enable hyperdoping of impurities. This process overcomes the bandgap constraints of crystalline silicon, resulting in heightened absorption across a broad spectral range spanning from ultraviolet to infrared wavelengths, therefore commonly referred to as black silicon (b‐Si). The b‐Si demonstrates significant changes in optoelectronic properties, making it highly promising for applications in silicon photonics. Specifically, b‐Si photodetectors exhibit distinct advantages in terms of high photoelectric gain at low voltage, ultrabroadband spectral responsivity, large dynamic range, and suitability for operation over a wide temperature range. These properties address the limitations of traditional silicon photodetectors, showcasing great potential for applications in optoelectronic integration, artificial intelligence, information technology, energy devices, and beyond. This review focuses on b‐Si achieved through ultrafast laser processing, with a special emphasis on its applications in photodetectors. The mechanism of ultrafast laser irradiation and the properties of hyperdoped silicon are discussed. Then, the research progresses and state‐of‐the‐art b‐Si photodetectors are introduced, as well as working mechanism and potential application expansion. Finally, the development prospects of b‐Si photodetectors based on ultrafast laser hyperdoping are predicted. [ABSTRACT FROM AUTHOR]

Charge carrier lifetime is a crucial material parameter in optoelectronic devices and knowing the dominant recombination channels points the way for improvements. The effective carrier lifetime τeff of surface‐passivated hyperdoped (hSi) and nonhyperdoped “black” (bSi) silicon by quasi‐steady‐state photoconductance decay (QSSPC) measurements and its evolution upon controlled wet‐chemical etching are studied. Sample preparation involves the irradiation of Si by numerous ultrashort laser pulses either in SF6 for hSi or ambient atmosphere for bSi. Findings suggest that the hSi is composed of a double layer: 1) an amorphous resolidified top layer with about 92% of the total incorporated sulfur that accounts for the sub‐bandgap absorptance and 2) a crystalline layer underneath in which sulfur concentration tails off toward the Si substrate. The effective lifetime is deconstructed by a 1D simulation to quantify the impact of the local lifetime of the defect‐rich top layer, τtop. It is found that by the QSSPC method, a maximum τtop for 1) can be estimated. For 2), τtop between 2 and 8 ns is estimated. The bSi sample shows a faster lifetime recovery upon etching which suggests that in hSi samples purely laser‐induced defects are not limiting the carrier lifetime compared to sulfur‐related defects. [ABSTRACT FROM AUTHOR]

As building blocks of multifunctional materials involving coupling at the nanoscale, highly doped semiconductor nanocrystals are of great interest for potential applications in nanophotonics. In this work, we investigate the plasmonic properties of highly doped Si nanocrystals embedded in a silica matrix. These materials are obtained by evaporation of heavily phosphorus-doped SiO/SiO2 multilayers in an ultrahigh vacuum chamber followed by rapid thermal annealing. For P contents between 0.7 and 1.9 atom %, structural investigations at the nanoscale give clear evidence that P atoms are mainly located in the core of Si nanocrystals with concentrations reaching up to 10 atom %, i.e., well beyond the solid solubility limit of P in bulk Si. Alloying and formation of SiP nanoparticles are observed for P contents exceeding 4 atom % in the multilayer. Infrared absorption measurements give evidence of a localized surface plasmon resonance located in the 3–6 μm range. A core–shell structure was used to model Si nanocrystals embedded in a silica matrix. Based on the Mie theory and the Drude model, both the mobility and the free charge carrier density were extracted from the simulation, with values reaching 27 cm2 V–1 s–1 and 2.3 × 1020 cm–3, respectively. This results in a dopant activation rate of about 8%. [ABSTRACT FROM AUTHOR]

Compared to conventional oven-based annealing in ambient air of a silicon surface layer nanotextured and hyperdoped in CS 2 fluid by femtosecond laser (black nano-silicon), low-intensity nanosecond laser annealing facilitated its delicate recrystallization, preserving quasi-regular nanoscale topography and high n-doping concentration by sulfur donor impurities. The retained and recrystallized topography of the laser-annealed nano-silicon with a few-percent doping level exhibits broadband optical absorption in the visible−near-infrared (vis−NIR) range, rendering this optical material promising for photovoltaic and IR-photonic applications. • Nanosecond laser annealing of a silicon, nanotextured and hyperdoped in CS 2 fluid by femtosecond laser carried out. • Two-wavelength scanning Raman microspectroscopy indicated almost complete recrystallization of the hyperdoped nanotexture. • The laser-annealed nano-silicon exhibited broadband (mid-IR-vis) reduced reflectance and transmittance. [ABSTRACT FROM AUTHOR]

Spectral range of crystalline silicon absorption could be extended to near- and even mid-infrared region by its hyperdoping via ion-implantation technology, requiring the following thermal annealing for removing ion-induced defects, recrystallizing the crystalline structure and activating the doping impurity. In this article, the crystalline structure, chemical and electrical characteristics of sulfur-hyperdoped silicon layers with broadly variable impurity concentration (1018-1021 cm−3) and annealed by a nanosecond laser were investigated for the first time by Raman, energy-dispersion x-ray and infrared spectroscopy, as well as by van der Paw and Hall measurements, respectively. The most preferable sulfur concentration for silicon hyperdoping from the point of view of impurity optical and electrical activation was found to be 1020 cm−3. [ABSTRACT FROM AUTHOR]

Sulfur hyperdoped silicon (Si:S) is a promising material for sub-bandgap photovoltaics or infrared photodetectors. However, previous publications show that a temperature step is necessary to improve device performance. This temperature step leads to a decrease in sub-bandgap absorptance, which is a major challenge. We show a post-treatment that increases the thermal stability of Si:S in terms of sub-bandgap absorptance, sheet carrier density and mobility. In addition, we investigate a post-treatment for optical reactivation of Si:S regarding sheet carrier density and mobility and thus gain atomistic insights into the reactivation step. [ABSTRACT FROM AUTHOR]

As the main component of silicon (Si)-based Optic Electronics Integrated Circuit (OEIC) chip, Si-based infrared photodetector operating at communication wavebands is very important. In this paper, we report a kind of chromium (Cr)-hyperdoped black Si material fabricated using femtosecond laser pulses irradiation. The concentration of the Cr atoms in the black Si layer exceeds 1020 cm−3 and the Cr-hyperdoped Si has a large sub-bandgap absorptance (~60% for $1.31 \boldsymbol {\mu }\text{m}$). The deep-energy level introduced by Cr impurity is 0.39 eV below the bottom of conduction band and thus the ionized electron concentration is very low (~1015 cm−3). Owing to the excellent sub-bandgap absorption of Cr-hyperdoped Si, face-to-face black Si photodiodes are fabricated. Under illumination of $1.31 \boldsymbol {\mu }\text{m}$ light, the responsivity of the photodiodes based on N+-N junction reaches 0.57 A/W at 4.3 V bias. In addition, the rise and delay time of the device to the infrared light are on the order of milliseconds. [ABSTRACT FROM AUTHOR]

Layers of selenium-hyperdoped silicon with dopant concentration of up to (4–6) × 1020 cm–3 that exceeds the limit of equilibrium solubility of this impurity by 4 orders of magnitude were obtained using ion implantation followed by pulsed laser annealing (PLA) at pulse energy densities of W = 0.55, 0.8, 1.0, 1.5, 2.0, and 2.5 J/cm2. Rutherford back scattering of helium ions demonstrated that up to 60–70% of introduced impurity occupied silicon lattice sites. Selenium-hyperdoped layers exhibited substantial absorption (36–40%) in the wavelength range of 1100–2400 nm. Absorption spectra of silicon layers obtained at different regimes of laser annealing are compared with each other. It is demonstrated that annealing at W = 2.0 J/cm2 is optimal from the point of view of achieving maximum structural perfection of hyperdoped silicon layers. This factor is very important for application of formed structures in photodetectors and components of solar energy systems. At the same time, absorption in the visible and near IR wavelength ranges attained maximum value after annealing at W = 1.0 J/cm2 and remained nearly unchanged with further increase in the pulse energy density. [ABSTRACT FROM AUTHOR]

[Display omitted] • The highest doping level in Bi-hyperdoped Si is achieved via a chip-technology compatible approach. • The epitaxial regrowth of Bi-hyperdoped Si layers and the Bi impurity substitution are confirmed. • In the Bi-hyperdoped Si, a record-high electron-concentration of 1.7 × 1020 cm−3 and a prominent electrical-activation-yield above 50 % are measured. • The magneto-transport behavior in Bi-hyperdoped Si epilayers is tunable by controlling donor concentration, providing a new platform for designing nonmagnetic spin-transport devices. During the past decades, excavating the novel functional materials towards CMOS-compatible spin-transport devices has been treated as one of the most urgent tasks to revolutionize the current Si-based nonmagnetic spintronics. Among various strategies, triggering the exotic physics in Si via utilizing heavy-element hyperdoping is the most straightforward way to achieve the abovementioned expectation. In this work, by using liquid phase epitaxy growth, we have achieved the highest Bi doping level in Si up to 2.0 × 1021 cm−3. The resulting Bi-hyperdoped Si layers are confirmed to be single-crystalline and epitaxially regrown without extended defects or Bi agglomerates via various microstructural analysis. The Bi-hyperdoped Si layers exhibit a metallic-like behavior with the carrier densities up to 1.55 × 1015 cm−2 and a prominent electrical activation yield around 50 %. Negative magnetoresistance due to magnetic-field suppressed weak localization at both sides of the insulator-to-metal transition is observed. Tunable magneto-transport properties are realized in ultra-high Bi doped Si epilayers by controlling the donor concentration. This provides new possibilities for designing Si devices that integrate spin-charge conversion and spin transport. This work promises to enable heavy-element hyperdoped semiconductor epilayers as novel spin-based electronics material platform via a chip-technology compatible approach. [ABSTRACT FROM AUTHOR]

Si‐based photodetectors satisfy the criteria of being low‐cost and environmentally friendly, and can enable the development of on‐chip complementary metal‐oxide‐semiconductor (CMOS)‐compatible photonic systems. However, extending their room‐temperature photoresponse into the mid‐wavelength infrared (MWIR) regime remains challenging due to the intrinsic bandgap of Si. Here, we report on a comprehensive study of a room‐temperature MWIR photodetector based on Si hyperdoped with Te. The demonstrated MWIR p‐n photodiode exhibits a spectral photoresponse up to 5 µm and a slightly lower detector performance than the commercial devices in the wavelength range of 1.0–1.9 µm. The correlation between the background noise and the sensitivity of the Te‐hyperdoped Si photodiode, where the maximum room‐temperature specific detectivity is found to be 3.2 × 1012 cmHz1/2 W−1 and 9.2 × 108 cmHz1/2 W−1 at 1 µm and 1.55 µm, respectively, is also investigated. This work contributes to pave the way towards establishing a Si‐based broadband infrared photonic system operating at room temperature. [ABSTRACT FROM AUTHOR]

Silicon, as the earth-abundant semiconductor, has low cost and good compatibility with mature complementary metal-oxide-semiconductor technology. Therefore, instead of choosing the proper semiconductor with a specific bandgap energy, hyperdoping technique, which can introduce deep-level dopants and intermediate band into silicon, enable silicon to operate in infrared wavebands. Particularly, the hyperdoped silicon with transition metals, having low ionized impurity scatting, makes silicon a promising infrared detection material. In present work, zinc-hyperdoped silicon is fabricated by femtosecond pulsed laser irradiation. The doping concentration of zinc has exceeded 1019 cm−3, and even reached 1022 cm−3, which is about five orders of magnitude greater than the solid solubility of zinc in crystalline Si. The zinc-hyperdoped silicon shows sub-bandgap absorptance of 87.86 % at 1310 nm. Temperature-dependent Hall effect measurements prove that zinc doping results in acceptor energy level located at 0.520 eV above the valence band maximum. It is worth nothing that, zinc-oxygen related defect state results in donor energy level located at 0.252 eV below the conduction band minimum when lower laser fluence is used, which means the energy level of impurity is altered by the presence of undesignedly doped oxygen atoms, suggesting compound formation between the zinc atoms and oxygen atoms. • The concentration of Zn atoms is about five orders of magnitude greater than the solid solubility of Zn in crystalline Si. • Zn hyperdoping can achieve a nice tradeoff between sub-bandgap absorption and recombination within IB materials. • As deep level dopant, ionizing impurity scattering of Zn atoms has weak impact on the charge carrier transport process. • Zn-hyperdoped Si can extend the operating wavelength to shortwave infrared region. • Zn-hyperdoped Si exhibits dual conductive type that depends on the relative content of Zn and O in hyperdoped layer. [ABSTRACT FROM AUTHOR]

[Display omitted] • High level of Se substitution in the Si lattice is achieved by implantation with nanosecond pulse laser annealing. • Scanning tunneling spectroscopy reveals the intermediate band in Se hyperdoped Si. • The broad absorption IR band at 1–5 μm is attributed to interband transitions. In this work, we present the formation of silicon layers hyperdoped with selenium through Se implantation followed by pulsed laser annealing. The concentration depth distribution of Se atoms was investigated by Rutherford backscattering and X-Ray photoelectron spectroscopies. Scanning tunneling spectroscopy confirmed the formation of intermediate sub-band within Si band gap. The crystallinity of the doped silicon layer and the fraction of Se atoms in Si lattice sites were determined using backscattering yield analysis. Experimental and theoretical sub-band properties were compared and discussed. Notably, a significant increase in light absorption across a wide spectral region (0.2–23.0 μm) was observed, demonstrating the potential of selenium hyperdoping for enhancing infrared absorption in silicon. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ti-hyperdoped Si layer was formed via ns-laser melting of thin Ti films on intrinsic Si substrate. • N b of − 2.60 × 1020 cm−3, ρ of 3.7 × 10−3 Ω·cm, and NIR absorptance of ∼ 63% were reached. • Hyperdoping depth and concentration were controlled by a suitable t film and matched F. • A microstructural surface of nanocrystal clusters and a TiSi 2 phase were observed. • Hyperdoping mechanism was clarified by heat transfer, melting, impurity incorporation, resolidification, and crystallization. Pulsed-laser melting of thin films has attracted increasing attention for manufacturing hyperdoped semiconductors as photovoltaic materials. However, most of the research on pulsed-laser melting of thin films has been focused on the femtosecond-laser hyperdoping, leaving the process and mechanism of nanosecond-laser (ns-laser) hyperdoping largely unexplored. Therefore, high-resistivity (>104 Ω·cm) intrinsic Si wafers were hyperdoped with Ti via thin Ti film deposition and ns-laser melting. Thus, the bulk carrier concentration and resistivity of the Ti-hyperdoped Si (Si:Ti) layer reached − 2.60 × 1020 cm−3 and 3.7 × 10−3 Ω·cm, respectively. Furthermore, the infrared absorptance of the Si:Ti layer increased to ∼ 63% in the wavelength range of 1100–2500 nm, which was much higher than that of intrinsic Si crystal (∼0%). In addition, the Si:Ti layer showed a nanocrystalline structure, and its average depth increased from 230 to 515 nm with the increase of Ti film thickness from 60 to 150 nm and ns-laser fluence from 2.27 to 2.70 J∙cm−2. Meanwhile, Ti impurities were fully distributed in these Si:Ti layers. The normalized concentrations of Ti increased from 2.4 at. % to 7.4 at. %. Moreover, the high concentrations of Ti impurity atoms chemically bound with Si atoms formed a TiSi 2 phase. Finally, the ns-laser hyperdoping mechanism was proposed as follows. During the ns-laser irradiation, the Ti films were melted at first, and a large part of laser heat was transferred to the intrinsic Si substrate surface to form Ti and Si molten mixed layers. Then, the heat promoted the incorporation of Ti into the Si lattice, forming bonds. Finally, the Si:Ti layer was formed via resolidification and crystallization after ns-laser treatment. [ABSTRACT FROM AUTHOR]

Abstract: The Ga-assisted formation of Ge nanorods and nanowires in solution has been demonstrated and a catalytic activity of the Ga seeds was observed. The synthesis of anisotropic single-crystalline Ge nanostructures was achieved at temperatures as low as 170 °C. Gallium not only serves as nucleation seed but is also incorporated in the Ge nanowires in higher concentrations than its thermodynamic solubility limit.Graphical abstract: [ABSTRACT FROM AUTHOR]

Abstract: Hyperdoping consists of the intentional introduction of deep‐level dopants into a semiconductor in excess of equilibrium concentrations. This causes a broadening of dopant energy levels into an intermediate band between the valence and the conduction bands. Recently, bulk Si hyperdoped with chalcogens or transition metals is demonstrated to be an appropriate intermediate‐band material for Si‐based short‐wavelength infrared photodetectors. Intermediate‐band nanowires can potentially be used instead of bulk materials to overcome the Shockley–Queisser limit and to improve efficiency in solar cells, but fundamental scientific questions in hyperdoping Si nanowires require experimental verification. The development of a method for obtaining controlled hyperdoping levels at the nanoscale concomitant with the electrical activation of dopants is, therefore, vital to understanding these issues. Here, this paper shows a complementary metal‐oxide‐semiconductor (CMOS)‐compatible technique based on nonequilibrium processing for the controlled doping of Si at the nanoscale with dopant concentrations several orders of magnitude greater than the equilibrium solid solubility. Through the nanoscale spatially controlled implantation of dopants, and a bottom‐up template‐assisted solid phase recrystallization of the nanowires with the use of millisecond‐flash lamp annealing, Se‐hyperdoped Si/SiO2 core/shell nanowires are formed that have a room‐temperature sub‐bandgap optoelectronic photoresponse when configured as a photoconductor device. [ABSTRACT FROM AUTHOR]

We perform IR nanosecond laser microtexturing and hyperdoping of commercial silicon wafers under a 5 mm thick carbon-disulfide liquid layer at broadly variable laser exposures from incomplete to multi-shot irradiation per spot. All these samples demonstrate that the mid-IR-range optical densities and sulfur-donor dopant vary concentrations nonmonotonously versus laser intensity and scanning speed due to surface ablation and its vapor bubble screening. This enabled us, for the first time, to distinguish the predominating MIR-light trapping in microstructured Si at high exposures and a characteristic sulfur-donor MIR-absorption at lower exposures at rather constant sulfur concentrations. The characteristic interband sulfur-donor IR-absorption exhibits increasing magnitude for larger dissolved sulfur clusters versus increase in total sulfur concentration, paving the way for spatially- and spectrally-engineered MIR-absorption in hyperdoped Si for thin-film photovoltaics. [ABSTRACT FROM AUTHOR]

In this study we use co-evaporation to grow In2S3 thin films on glass substrates and X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) to analyse the structural properties of annealed In2S3 and V-doped In2S3 for intermediate band solar cell application. We find co-evaporated In2S3 to be polycrystalline on float glass and with improved crystallinity after annealing in S-atmosphere. We confirm that excessive incorporation of vanadium into the host structure is possible without formation of secondary crystalline phases. The analysis indicates a reduced crystalline quality after V doping. [ABSTRACT FROM AUTHOR]

Gold (Au)-doped-textured silicon (Si) material with a thermostable absorption below bandgap (>50%) is obtained by femtosecond laser irradiation. Although the concentration of Au impurity (1019 cm−3 ) in textured Si is at least four orders of magnitude greater than the solid solubility of Au in crystalline Si, the sheet carrier density (approximately 1010 cm−2) in Au-doped Si is very low due to a self-compensation effect of Au impurity in Si material. The infrared absorption of Au-doped Si is related to laser-induced-structural defects and sub-band absorption of deep energy levels of Au in Si, which is determined by temperature-dependent Hall Effect measurement. Besides supersaturated doping of Au, a gold silicide phase is formed at textured Si surface. [ABSTRACT FROM PUBLISHER]

We perform a single-shot IR nanosecond laser processing of commercial silicon wafers in ambient air and under a 2 mm thick carbon disulfide liquid layer. We characterize the surface spots modified in the liquid ambient and the spots ablated under the same conditions in air in terms of its surface topography, chemical composition, band-structure modification, and crystalline structure by means of SEM and EDX microscopy, as well as of FT-IR and Raman spectroscopy. These studies indicate that singlestep microstructuring and deep (up to 2-3% on the surface) hyperdoping of the crystalline silicon in its submicron surface layer, preserving via pulsed laser annealing its crystallinity and providing high (10 cm) spectrally flat near- and mid-IR absorption coefficients, can be obtained in this novel approach, which is very promising for thin-film silicon photovoltaic devices. [ABSTRACT FROM AUTHOR]

We have examined microstructures induced by pulsed-laser-melting for the Mn ion implanted Si using transmission electron microscopy. Single crystalline Si(0 0 1) wafers were irradiated with 65 keV and 120 keV Mn ions to a fluence of 1.0 × 10 16 /cm 2 at room temperature. The ion beam-induced amorphous layers in the as-implanted samples were melted and resolidified by pulsed YAG laser irradiation. After laser irradiation with appropriate laser fluence, the surface amorphous layers recrystallize into the single crystalline Si. The Mn concentration becomes higher in the near-surface region with increasing the number of laser shots. The migrated Mn atoms react with Si atoms and form the amorphous Mn–Si in the Si matrix. [ABSTRACT FROM AUTHOR]

• Silver-hyperdoping in silicon (Si:Ag) results in the sub-bandgap photoresponse. • The carrier transmission is greatly improved in graphene. • A high-responsivity graphene/hyperdoped-silicon heterostructure infrared photodetector with high responsivity is obtained. Strong sub-bandgap absorption of hyperdoped silicon caused by an impurity deep band has attracted a lot of interest in recent years, which is promising for photodetector application. Currently, the responsivity of hyperdoped Si photoconductors is still low due to the carrier scattering by hyperdoping induced defects, which impedes their application. Here, we prepare a high-responsivity silver hyperdoped silicon heterostructure infrared photoconductor by using graphene as the carrier transport layer. The characterization of the dark I-V curve illustrates that the efficiency of the separation and collection efficiency of carriers of the Si: Ag/Gr photoconductor was obviously improved, compared with the conventional Si: Ag photoconductor. Under a low bias of 0.3 V, the external quantum efficiency (EQE) of the Si: Ag/Gr photoconductor reached 97.26% at 1310 nm and 7.37% at 1550 nm, respectively. These results pave a new way to the hyperdoped silicon heterostructure infrared photodetectors with high responsivity. [ABSTRACT FROM AUTHOR]

Hyperdoping silicon nanocrystals (Si NCs) to a concentration exceeding the solubility limit of a dopant may enable their novel applications. Here, the successful hyperdoping of Si NCs with boron (B) and phosphorus (P) is demonstrated, which are the most important dopants for Si. Despite the hyperdoping, the diamond structure of Si NCs is hardly modified. There are both electrically active B and P in hyperdoped Si NCs. It is proposed that the hyperdoping is made possible mainly by the kinetics in the nonthermal plasma synthesis of Si NCs. Collision between Si NCs and B or P atoms and the binding energy of B or P at the NC surface are critical to the understanding on the differences in the doping efficiency and dopant distribution between B and P. B-hyperdoping-induced tensile stress needs to be taken into account in the investigation on the doping and oxidation of Si NCs. [ABSTRACT FROM AUTHOR]

In the field of current silicon (Si)-based photonics, photodetectors are required to detect the light in near-infrared region (>1100 nm), at the same time, they should meet the requirements of high sensitivity, thermal stability, and good compatibility with CMOS (Complementary Metal-Oxide-Semiconductor Transistor) technology process. In order to extend the detection wavelength of Si to near-infrared region, introducing intermediate band (IB) into the bandgap of Si is an effective method, which can be realized by hyper-doping of deep-levels impurities. As nonequilibrium doping technique, ion implantation and pulsed laser annealing can make the concentration of impurities exceed the equilibrium solubility limit in Si by several orders of magnitude. In the past twenty years, the potential of hyper-doped Si as an IB material has aroused new interest in the field of infrared photodetection. In this review, we focus on the infrared absorption and infrared detection of hyper-doped Si by ion implantation and pulsed laser annealing. The infrared absorption mechanism, and influencing factors of infrared absorptance for hyper-doped Si with chalcogens and transition metals have been emphasized. For infrared photodetectors, the latest research on the responsivity and external quantum efficiency of photodetectors based on hyper-doped Si has been reviewed. Finally, some suggestions have been provided to improve the infrared absorption and performance of photodetectors. This work summarizes the latest progress of infrared absorption and infrared photodetectors by ion implantation and pulsed laser annealing, which will broaden the application of Si-based infrared photodetectors in the Si-based photonics integration. [ABSTRACT FROM AUTHOR]

The doping of near-surface region of single crystalline p -type Si by Fe impurity under irradiation by the low-energy and high-current Xe+ ion beam is investigated. The recoil-atom implantation method was applied which utilizes simultaneous sputtering of Fe target with irradiation of the deposited Fe atoms on the Si substrate surface by Xe+ ion beam. The resulting incorporation of Fe atoms into Si leads to formation of very thin (~5 nm) highly doped (>1022 at/cm3) surface layer (Si:Fe) containing Si and α-Fe nanoparticles with sizes of 5–20 nm. Such a layer demonstrates ferromagnetism at T = 10 K and superparamagnetism at 300 K. Inversion of the conductivity type (from p -to n -type) in the heavily doped Si:Fe layer and formation of n-p junction to the substrate is observed. A photoresponse of thus obtained n -Si:Fe/ p -Si diode structure demonstrates an intense signal in the wavelength range of 500–1200 nm with a maximum at about 950 nm under the low reverse bias voltage (U = 1 V), whose integral intensity is comparable with that for commercial silicon photodiode at U = 10 V. [ABSTRACT FROM AUTHOR]

Electronic properties of silicon, the most important semiconductor material, are controlled through doping. The range of achievable properties can be extended by hyperdoping, i.e., doping to concentrations beyond the nominal equilibrium solubility of the dopant. Here, hyperdoping is achieved in a laser pyrolysis reactor capable of providing nonequilibrium conditions, where doping is governed by kinetics rather than thermodynamics. High resolution scanning transmission electron microscopy (TEM) with energy‐dispersive X‐ray spectroscopy shows that the boron atom distribution in the hyperdoped nanoparticles is relatively uniform. The hyperdoped nanoparticles demonstrate tunable localized surface plasmon resonance (LSPR) and are stable in air for periods of at least one year. The hyperdoped nanoparticles are also stable upon annealing at temperatures up to 600 °C. Furthermore, boron hyperdoping does not change the diamond cubic crystal structure of silicon, as demonstrated in detail by high flux synchrotron X‐ray diffraction and pair distribution function (PDF) analysis, supported by high‐resolution TEM analysis. Boron‐hyperdoped silicon nanocrystals produced by laser pyrolysis of silane and diborane maintain the crystal structure of silicon with uniformly distributed boron, revealed by high‐resolution scanning transmission electron microscopy and high flux synchrotron X‐ray diffraction with pair distribution function analysis. As‐synthesized nanoparticles with 0.4–42.5 atom percent boron exhibit stable and tunable localized surface plasmon resonance at mid‐infrared wavelengths. [ABSTRACT FROM AUTHOR]

A low-temperature chemical vapor growth of Ge nanowires using Ga as seed material is demonstrated. The structural and chemical analysis reveals the homogeneous incorporation of ∼3.5 at. % Ga in the Ge nanowires. The Ga-containing Ge nanowires behave like metallic conductors with a resistivity of about ∼300 μΩcm due to Ga hyperdoping with electronic contributions of one-third of the incorporated Ga atoms. This is the highest conduction value observed by in situ doping of group IV nanowires reported to date. This work demonstrates that Ga is both an efficient seed material at low temperatures for Ge nanowire growth and an effective dopant changing the semiconductor into a metal-like conductor.