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In this study, a SiO2 layer containing YF3:Yb3+/Er3+ phosphors was deposited within matrix-grooves on the back side of silicon solar cells to enable the up-conversion (UC) of near-infrared (NIR) wavelengths with the aim of enhancing energy conversion efficiency. The chemical and optical characteristics of the UC layer were identified using energy-dispersive X-ray spectroscopy and photoluminescence measurements. We also characterized the electrical and optical performance of cells featuring a SiO2 layer with and without NIR-UC phosphors particles of various concentrations in terms of external quantum efficiency and photovoltaic current voltage. Efficiency was shown to increase with an increase in the concentration of NIR-UC phosphors. The efficiency of the cell with a SiO2 layer that included 30 wt% YF3:Yb3+/Er3+ phosphors exceeded the efficiency of a bare solar cell by 13.26%.

This paper studied characterized the plasmonic effects of silver nanoparticles (Ag-NPs), the luminescent down-shifting of Eu-doped phosphor particles, and the metal-enhanced fluorescence (MEF) achieved by combining the two processes to enhance the conversion efficiency of silicon solar cells. We obtained measurements of photoluminescence (PL) and external quantum efficiency (EQE) at room temperature to determine whether the fluorescence emissions intensity of Eu-doped phosphor was enhanced or quenched by excitation induced via surface plasmon resonance (SPR). Overall, fluorescence intensity was enhanced when the fluorescence emission band was strongly coupled to the SPR band of Ag-NPs and the two particles were separated by a suitable distance. We observed a 1.125× increase in PL fluorescence intensity at a wavelength of 514 nm and a 7.05% improvement in EQE (from 57.96% to 62.05%) attributable to MEF effects. The combined effects led to a 26.02% increase in conversion efficiency (from 10.23% to 12.89%) in the cell with spacer/NPs/SOG-phosphors and a 22.09% increase (from 10.23% to 12.48%) in the cell with spacer/SOG-phosphors, compared to the bare solar cell. This corresponds to an impressive 0.85% increase in absolute efficiency (from 12.04% to 12.89%), compared to the cell with only spacer/SOG.

This study reports the use of spectral modulation to solve photocurrent mismatch between sub-cells of triple-junction GaAs solar cell as well as to increase conversion efficiency by using a specific thickness of single antireflection TiO2-layer.

In this study, we investigated the electrical and optical performance of single-junction GaAs solar cells coated with an antireflective layer of indium tin oxide (ITO) via thermal sputtering deposition followed by a layer of SiO2 doped with 3 wt% europium-doped (Eu-doped) silicate phosphors via spin-on film technique. The chemical composition of the Eu-doped silicate phosphors was analyzed using energy-dispersive X-ray spectroscopy and the luminescent downshifting (LDS) characteristics were examined in terms of photoluminescence, optical reflectance, and external quantum efficiency (EQE) response. Reverse saturation-current and ideality factor were used to evaluate the passivation performance of ITO films thermal sputtered on GaAs solar cells. The antireflective performance of the ITO film and the LDS effects of the Eu-doped silicate phosphor coatings were respectively evaluated in terms of optical reflectance and EQE response. The enhancement of photovoltaic performance due to LDS effects was confirmed by photovoltaic current density–voltage characteristics of cells under one-sun air mass 1.5G solar simulations. The efficiency enhancement of the cell with only an ITO/SiO2 antireflective layer was 18.39%, whereas the cells coated a SiO2 layer that included various species of Eu-doped phosphors (species-A, species-B, or species-C) on ITO achieved efficiency enhancements of 19.83%, 20.29%, and 21.07%, respectively.

This paper experimentally demonstrates the benefits of combining an up-conversion (UC) layer containing Yb/Er-doped yttrium oxide-based phosphors with a plasmonic scattering layer containing indium nanoparticles (In-NPs) in enhancing the photovoltaic performance of textured silicon solar cells. The optical emissions of the Yb/Er-doped phosphors were characterized using photoluminescence measurements obtained at room temperature. Optical microscope images and photo current-voltage curves were used to characterize the UC emissions of Yb/Er-doped phosphors under illumination from a laser diode with a wavelength of 1550 nm. The plasmonic effects of In NPs were assessed in terms of absorbance and Raman scattering. The performance of the textured solar cells was evaluated in terms of optical reflectance, external quantum efficiency, and photovoltaic performance. The analysis was performed on cells with and without a UC layer containing Yb/Er-doped yttrium oxide-based phosphors of various concentrations. The analysis was also performed on cells with a UC layer in conjunction with a plasmonic scattering layer. The absolute conversion efficiency of the textured silicon solar cell with a combination of up-conversion and plasmonic-scattering layers (15.43%) exceeded that of the cell with an up-conversion layer only (14.94%) and that of the reference cell (14.45%).

In this study, we examined efforts to increase the photovoltaic performance of GaAs single-junction solar cells using spectral conversion layers, respectively, composed of europium-doped (Eu-doped) phosphors, ytterbium/erbium-doped (Yb/Er-doped) phosphors, and a combination of Eu-doped and Yb/Er-doped phosphors. Spin-on film deposition was used to apply the conversion layers, all of which had a total phosphor concentration of 3 wt%. The chemical compositions of the phosphors were examined by energy-dispersive X-ray spectroscopy. The fluorescence emissions of the phosphors were confirmed by using photoluminescence measurements. Under laser diode excitation at 405 nm, we observed green luminescent downshift (LDS) emissions by Eu-doped phosphors at wavelengths of 479 nm to 557 nm, and under excitation at 980 nm, we observed red up-conversion (UC) emissions by Yb/Er-doped phosphors at wavelengths of 647 nm to 672 nm. The spectral conversion layers were characterized in terms of optical reflectance, external quantum efficiency, and photovoltaic current and voltage under AM 1.5 G simulations. The conversion efficiency of the cell combining Eu-doped and Yb/Er-doped phosphors (23.84%) exceeded that of the cell coated with Yb/Er-doped phosphors (23.72%), the cell coated with Eu-doped phosphors (23.19%), and the cell coated without phosphors (22.91%).

This paper presents a novel front-illuminated InAlAs/InGaAs separate absorption, grading, field-control and multiplication (SAGFM) avalanche photodiodes (APDs) with a mesa-structure for high speed response. The electric fields in the InAlAs-multiplication layer and InGaAs-absorption layer enable high multiplication gain and high-speed response thanks to the thickness and concentration of the field-control and multiplication layers. A mesa active region of 45 micrometers was defined using a bromine-based isotropic wet etching solution. The side walls of the mesa were subjected to sulfur treatment before being coated with a thick polyimide layer to reduce current leakage, while lowering capacitance and increasing response speeds. The breakdown voltage (VBR) of the proposed SAGFM APDs was approximately 32 V. Under reverse bias of 0.9 VBR at room temperature, the proposed device achieved dark current of 31.4 nA, capacitance of 0.19 pF and multiplication gain of 9.8. The 3-dB frequency response was 8.97 GHz and the gain-bandwidth product was 88 GHz. A rise time of 42.0 ps was derived from eye-diagrams at 0.9 VBR. There was notable absence of intersymbol-interference and the signals remained error-free at data-rates of up to 12.5 Gbps.

This paper demonstrates the fabrication of plasmonic silicon (Si) solar cells with a matrix comprising a pattern of silver nanoparticles (Ag-NPs) surrounded by indium nanoparticles (In-NPs). We examined the plasmonic-modulated light scattering induced by Ag-NPs/In-NPs matrices with various degrees of coverage using optical as well as electrical measurements. The Raman scattering of In-NPs and Ag-NPs was characterized using a semiconductor laser at a wavelength of 532 nm and output power of 0.36 W. We also measured the optical reflectance and external quantum efficiency response of various solar cells. We achieved impressive results with regard to plasmonic-modulated light scattering through the implementation of a matrix that included Ag-NP coverage of 20% and In-NP coverage of 80% over an area of 4 × 4 mm 2 . This resulted in a 9.93% increase in short-circuit current density (from 31.91 mA/cm 2 to 35.08 mA/cm 2 ) and a 10.12% increase in conversion efficiency (from 13.04% to 14.36%), compared to cells with uniformly distributed Ag-NPs.

In this study, the high conversion efficiency of textured silicon solar cells based on an ITO/TiO2/Si metal–oxide–semiconductor (MOS) structure and biasing effects was experimentally demonstrated. An impressive conversion efficiency of >20% was obtained through an increase in the absorption volume and through the efficient collection of the generated photo-carriers when the biasing voltage was applied on the ITO-transparent electrode. The optical reflectance, dark current–voltage (I–V), external quantum efficiency (EQE) and photovoltaic current density–voltage (J–V) under one-sun AM 1.5G illumination of the MOS structure solar cells without voltage biasing were characterized firstly. Then the photovoltaic J–V curves of the MOS structure solar cells with biasing voltages from 0 to 3 V were measured and compared. Significant increases in short-circuit current and conversion efficiency were observed when the biasing voltage was increased from 0 to 3 V using an external voltage power supply. In addition, the integration of a photovoltaic biasing source using a series of connected p–n junction solar cells (instead of an external voltage power supply) with a MOS structure solar cell on a ceramic platform to enhance the MOS structure solar cell efficiency was demonstrated for the first time in textured silicon solar cells.

This paper reports impressive enhancements in the efficiency of crystalline silicon solar cells through the application of a Eu-doped silicate phosphor luminescent downshifting (LDS) layer controlled by spin-on film technique. Surface morphology was examined using scanning electron microscope (SEM), chemical composition was analyzed using energy dispersive spectroscopy (EDS), and fluorescence emission was characterized using photoluminescence (PL) measurements at room temperature. The optical reflectance, absorbance, and external quantum efficiency (EQE) response of SiO 2 -coated cells with and without Eu-doped silicate phosphor were measured and compared. An 18.77% improvement in efficiency was achieved, as determined by photovoltaic current–voltage measurement under one-sun AM 1.5 G illuminations.

This study experimentally examined the plasmonic near-field and far-field effects of two-dimensional (2-D) indium-nanoparticles (In-NPs) embedded within an anti-reflective SiO2 layer on the optical and electrical characteristics of silicon solar cells. The dimensions and profiles of the 2-D In-NPs were derived from scanning electron microscope images (top-view and side-view) using Image-J software. The surface plasmon resonance of the 2-D In-NPs was estimated from Raman scattering and absorbance measurements. Measurements of optical reflectance and external quantum efficiency revealed that near-field and far-field plasmonic effects depended on the thickness of the spacer and capping layers. The influence of these phenomena on photovoltaic performance was confirmed in terms of photovoltaic current density-voltage under AM 1.5 G illumination. The application of a 90-nm thick SiO2 anti-reflective layer was shown to enhance conversion efficiency by 23.85% (compared to the bare reference cell), and the inclusion of In-NPs between an 18-nm thick spacer layer and 72-nm thick capping layer extended this improvement to 34.16%.

In this study, we sought to enhance the output power and conversion efficiency of textured silicon solar cells by layering two-dimensional indium nanoparticles (In NPs) within a double-layer (SiNx/SiO2) antireflective coating (ARC) to induce plasmonic forward scattering. The plasmonic effects were characterized using Raman scattering, absorbance spectra, optical reflectance, and external quantum efficiency. We compared the optical and electrical performance of cells with and without single layers and double layers of In NPs. The conversion efficiency of the cell with a double layer of In NPs (16.97%) was higher than that of the cell with a single layer of In NPs (16.61%) and greatly exceeded that of the cell without In NPs (16.16%). We also conducted a comprehensive study on the light-trapping performance of the textured silicon solar cells with and without layers of In NPs within the double layer of ARC at angles from 0&deg, to 75&deg, The total electrical output power of cells under air mass (AM) 1.5 G illumination was calculated. The application of a double layer of In NPs enabled an impressive 53.42% improvement in electrical output power (compared to the cell without NPs) thanks to the effects of plasmonic forward scattering.

In this work, a planar-type top-illuminated high-responsivity InP-based avalanche photodetector (APD) was fabricated and characterized. The dark current of 0.55 nA, capacitance of 0.237 pF, responsivity of 12.2 A/W were obtained when APD operated at 0.95 breakdown voltage (Vbr). The eye diagrams of the fabricated APD under 0.95 VBR to the pseudorandom NRZ code of length 231-1 at 2.5–10 Gb/s were measured. The absence of significant intersymbol interference and the error free for the signals up to 10 Gb/s can be achieved.

This study demonstrates high-efficiency (23.72%) single-junction GaAs solar cell coated with species of NIR up-conversion phosphors layer on the front-side surface by spin-on-film deposition, compared to 19.36% efficiency of the reference single-junction GaAs solar cell.

Surface properties of a thin-film p-on-n silicon solar cell with a subwavelength nanoporous structure fabricated on an emitter layer by using metal-assisted chemical etching (MACE) were investigated through an experiment and simulation. After 10-s MACE processing, the conversion efficiency increased by 43.09% (from 5.64% to 8.07%) was obtained, compared with a reference solar cell without MACE. The simulation result indicated that the surface recombination velocity was an exponential function of the etching time from 0 to 30 s, and showed close agreement with the experimental data.

In this study, the enhancement of silicon solar cell photovoltaic performance by means of indium nanoparticles (In NPs) deposited on the TiO2 space layer and capped with an Al2O3 antireflective layer is demonstrated. The impressive performance enhancement is attributed to the plasmonic scattering of broadband light which occurs as a result of the Al2O3/In NPs/TiO2 antireflective coating (PARC) surface structure. The optical reflectance, photovoltaic current-voltage (I–V), external quantum efficiency (EQE), and photovoltaic performance as a function of the incident angles are measured and compared. The experimental results show that the reflectance decreases with increasing TiO2 thickness and that the lowest reflection point of the spectrum was red-shifted by the use of a PARC surface structure. EQE was significantly enhanced between 400 and 1050 nm wavelengths and much high EQE of 85% were observed for the cell with In NPs embedded in the 65-nm Al2O3/20 nm TiO2 layer structure. In comparison to a bare reference solar cell, an efficiency enhancement of 54.47% (from 10.96% to 16.93%) and a short-circuit current density enhancement of 52.83% (from 26.10 to 39.89 mA/cm2) were obtained for the cell with a 65-nm Al2O3/In NPs/20-nm TiO2 antireflection structure under normal incident illumination. In addition, for incident angles from 0° to 15°, the 0.78% decrease in conversion efficiency (from 16.71% to 16.58%) of the cell with the PARC surface structure was less than the 3.28% (from 13.86% to 13.49%) decrease of the cell with 65-nm Al2O3/20-nm TiO2 double layer antireflective coating (DL-ARC) due to the plasmonic scattering of broadband light.

This study employed spin-on film (SOF) technology for the fabrication of phosphorus diffusion and multi-layer anti-reflective coatings (ARCs) with a graded index on silicon (Si) wafers. Low cost and high efficiency solar cells are important issues for the operating cost of a photovoltaic system. SOF technology for the fabrication of solar cells can be for the achievement of this goal. This study succeeded in the application of SOF technology in the preparation of both phosphorus diffusion and SiO 2 /graded index TiO 2 ARCs for Si solar cells. Optical properties of TiO 2 , SiO 2 , and multi-layer SiO 2 /TiO 2 deposition by SOF are characterized. Electrical and optical characteristics of the fabricated solar cells are measured and compared. An impressive efficiency of 18.25% was obtained by using the SOF processes.

This study presents high efficiency InGaP/InGaAs/Ge triple-junction (3-J) solar cells incorporated in the middle cell with layers of InGaAs/GaAs quantum dots (QDs) grown by metal organic chemical vapor deposition to achieve 33.5% conversion efficiency (η) under one-sun AM 1.5 G illumination. We investigated the epitaxial structure and optical and electrical properties of InGaP/InGaAs/Ge 3-J solar cells with and without layers of QDs. We then measured X-ray diffraction (XRD), photoluminescence (PL), optical reflectance, dark and photovoltaic current–voltage (I–V) characteristics, external quantum efficiency (EQE) response, and capacitance–voltage (C–V) as a function of frequency under dark and illuminated conditions at room temperature. The use of 50 pairs of In0.7Ga0.3As (QD)/GaAs (Barrier) QD structure produced an impressive 35% enhancement in EQE at wavelengths of 900–930 nm. This resulted in a short-circuit current density of 15.43 mA/cm2, an open-circuit voltage of 2.54 V, a fill factor of 84.7%, and a η of 33.5%. The 3-J cell with the proposed layers of QDs also demonstrated a 1.0% absolute gain in efficiency compared with a reference cell without QDs. Our XRD, PL, and C–V results revealed that highly stacked InGaAs/GaAs QD layers of high quality can be grown with very little degradation in crystal quality and without the need for strain compensation techniques. Copyright © 2015 John Wiley & Sons, Ltd.

Plasmonic effects of silver nanoparticles (Ag NPs) of various dimensions embedded and non-embedded in silicon dioxide antireflective coating (SiO2 ARC) deposited by electron-beam evaporation on silicon (Si) solar cells are characterized. Raman scattering and absorbance measurements were used to examine plasmonic resonance absorption of Ag NPs with various particle dimensions and different dielectric environments. The obtained Raman and absorbance results revealed that the large dimensions of Ag NPs exhibited much impressive plasmonic resonance absorption. Furthermore, optical reflectance and photovoltaic current–voltage measurements were also used to confirm the photovoltaic performance enhancement inducing by plasmonic forward scattering of Ag NPs of various dimensions. Thus, the efficiency enhancement of 3.64, 7.42, and 10.24% for the solar cells with Ag NPs in diameter of 21, 25, 32 nm, respectively, embedded in SiO2 ARC was achieved due to plasmonic scattering inducing by Ag NPs, compared to the cell with a pure SiO2 ARC without Ag NPs.

The additional enhanced in conversion efficiency of the heterojunction with intrinsic thin-layer (HIT) silicon solar cell by using plasmonics scattering of indium nanoparticles (In NPs) was experimentally demonstrated. The conversion efficiency of 17.15% for the HIT solar cell with In NPs was obtained, compared to that of 16.63% for HIT solar cell without In NPs.

Integration of ITO/TiO2/Silicon (metal-oxide-semiconductor; MOS) structure silicon (Si) solar cell and a biasing source of p-n Si solar cells on silicon on insulator wafer was demonstrated. The photovoltaic performances of MOS-structure depended on the biasing voltage are measured and compared. Impressive enhanced in conversion efficiency of 10.63% was obtained when the MOS-structure solar cell was biased a photovoltaic voltage of 2.1V.

This study characterized the electrical and optical properties of single-junction GaAs solar cells coated with antireflective layers of silicon dioxide (SiO2), indium tin oxide (ITO), and a hybrid layer of SiO2/ITO applied using Radio frequency (RF) sputtering. The conductivity and transparency of the ITO film were characterized prior to application on GaAs cells. Reverse saturation-current and ideality factor were used to evaluate the passivation performance of the various coatings on GaAs solar cells. Optical reflectance and external quantum efficiency response were used to evaluate the antireflective performance of the coatings. Photovoltaic current-voltage measurements were used to confirm the efficiency enhancement obtained by the presence of the anti-reflective coatings. The conversion efficiency of the GaAs cells with an ITO antireflective coating (23.52%) exceeded that of cells with a SiO2 antireflective coating (21.92%). Due to lower series resistance and higher short-circuit current-density, the carrier collection of the GaAs cell with ITO coating exceeded that of the cell with a SiO2/ITO coating.

The combination of plasmonic scattering of silver nanoparticles (Ag-NPs) embedded in SiO2 layer and luminescent downshifting (LDS) of Eu-doped phosphor layer applied on silicon solar cells to enhance photovoltaic performances was demonstrated. By annealing 3, 5, and 7 nm thick silver films at 200 °C for 30 min under ambient H2 to form Ag NPs of various dimensions were obtained, which corresponding to the average dimensions of Ag-NPs are 20.13, 25.03, and 32.14 nm determining by SEM images. The optical and electrical properties of the cells with Ag-NPs embedded in a SiO2 antireflection coating (ARC) were characterized firstly by optical reflectance, absorbance, and external quantum efficiency (EQE) measurements. Larger Ag-NPs dimension of 32.14 nm exhibited a larger short-circuit current-density (Jsc) enhancement of 31.24%, which is higher than that of 30.90% for Ag-NPs dimension of 25.03 nm and 28.64% for Ag-NPs dimension of 20.13 nm. The combined effects of plasmonic scattering and LDS are studied by applying Ag-NPs and Eu-doped phosphor particles within SiO2 ARC, which the Jsc enhancement can be further enhanced from 28.64% to 29.37%.

In this study, we demonstrate the photovoltaic performance enhancement of silicon solar cell by means of plasmonics indium nanoparticles (In-NPs) layer embedded in SiO 2 antireflective coating (ARC). The optical reflectance, external quantum efficiency, and photovoltaic current-voltage are measured and compared. Impressive conversion efficiency enhancement of 35.94% for the cell with double In-NPs layers ARC, 34.77% for the cell with single In-NPs layer ARC, and 26.67% for the cell with a pure Si O2 ARC were obtained which is compared to the reference cells. Besides, the gain in absolute efficiency of 1.26-1.52% for the cells with In-NPs ARC was higher than that of the cell with a pure SiO 2 ARC, due to the contribution of plasmonics scattering of In-NPs.

The thermally deposited indium-tin-oxide (ITO) film on single-junction GaAs solar-cell as an excellent antireflection, passivation and window layer to achieve higher efficiency is demonstrated. The passivated characteristic of the ITO-film on GaAs solar-cell is examined by saturation-current and ideality factor. The antireflection of the ITO-film on GaAs solar-cell is revealed by optical-reflectance and external quantum-efficiency. The efficiency of 23.52% for the GaAs cell with ITO antireflection-coating (ARC) was higher than that of 21.92% for the GaAs cell with SiO 2 ARC.

This study presents high-efficiency of 23.52% single-junction GaAs solar cell using ITO-film as antireflection and passivation layer deposited by thermally-RF-sputtering. The impressive enhanced in efficiency of 8.94% was obtained, compared to the cell with SiO 2 -film.

A considerable enhancement in the photovoltaic performance of plasmonic silicon solar cells using indium nanoparticles on a patterned TiO2 matrix was demonstrated experimentally. For characterizing the optical properties of the patterned TiO2 matrix with and without indium nanoparticles, the indium nanoparticles were deposited on the reference samples with 30- and 59.5-nm thick TiO2 layers and on the test samples with a patterned TiO2 matrix of 30- and 59.5-nm thick profiles. The optical reflectance of all samples before and after depositing indium nanoparticles on the TiO2 layer was measured. To study plasmonics and anti-reflective effects on solar cells, the cells with indium nanoparticles on a patterned TiO2 matrix with a profile coverage levels of 20%, 40%, 60%, and 80% were characterized. The photovoltaic performance under one-sun AM 1.5 G illumination and the external quantum efficiency (EQE) of the cells were measured and compared. Compared to a bare cell, the plasmonic cell with a patterned TiO2 matrix of 40% profile coverage had a short-circuit current density (Jsc) enhancement of 30.98% (from 23.53 mA/cm2 to 30.82 mA/cm2) and a conversion efficiency (η) enhancement of 34.06% (from 9.63% to 12.91%). The improvements may be attributed to the combination of the reduction of reflection and the plasmonic scattering of incident-light by indium-nanoparticles on the patterned TiO2 matrix.

GaAs-based multi-junction solar cells (MJ-SCs) provide a wide solar-energy absorption-band (300–1800 nm), but designing and fabricating a broadband antireflection coating (ARC) are challenging. Because MJ-SCs are typically in a series that connects each subcell, the total output current is limited by the subcell that generates the smallest photocurrent. Thus, the ARC for MJ-SCs must be designed not only to obtain broadband absorption but also to minimize light reflection at the wavelength band of the current-limited cell. This study proposes a broadband SiO 2 /graded-index TiO 2 ARC for improving the current-limited subcell performance by using a hybrid deposition (e-beam evaporation and spin-on coating). A bottom TiO 2 layer and a top SiO 2 layer were deposited through e-beam evaporation, but the middle TiO 2 layer was deposited using spin-on coating because the refractive index values of the TiO 2 films could be tuned by applying the spin speed. Therefore, the graded-index TiO 2 layers were easily obtained using a hybrid deposition method. In addition, a suitable reflectance spectrum of an ARC structure for a middle-cell current-limited triple-junction (3-J) GaAs solar cell was simulated using commercial optical software. The photovoltaic current–voltage and external quantum efficiency (EQE) were measured and compared. The resulting improvements of a short-circuit current of 32.4% and conversion efficiency of 31.8% were attributed to an enhanced EQE of 32.97% as well as a low broadband reflectance exhibited on the middle cell of the 3-J GaAs solar cell with a SiO 2 /graded-index TiO 2 ARC.

In this paper, we propose and demonstrate a novel technique on improving the conversion efficiency for a metal-insulator-semiconductor (MIS) transistor-based solar cell by using a voltage biasing transparent electrode. The device structure is consisted of a Si-solar cell, a SiO 2 oxide layer, an indium tin oxide (ITO) transparent electrode, and two ohmic-contact electrodes for n-Si and p-Si. The used ITO transparent electrode with a high transmittance at the visible wavelengths and a low sheet resistance are obtained by a sputtering system. The performances of the bare Si-solar cell, the cell with ITO/SiO 2 layers, and the cell with ITO/SiO 2 layers and ITO electrode applying a bias voltage are sequentially characterized under AM1.5 solar illumination. Comparing the performance with the bare solar cell, the efficiency of the solar cell with ITO/SiO 2 films was enhanced of 34.3%. In which, the thin ITO/SiO 2 films provide a function like an anti-reflection (AR) coating. Furthermore, the efficiency as a function of bias-voltage was also observed when the ITO transparent electrode was biased at different volts. At 5 V biasing, the efficiency increasing of more 25.7% was obtained in our recently results, which compared the cell with zero volt biasing. The operation mechanism of the biasing dependent is also discussed.

We demonstrate experimentally the enhanced performance of the plasmonic silicon solar cell by using a nano-sized indium-particles and different thickness of TiO2 space layer structure. The optical reflectance, dark and photo current-voltage, and external quantum efficiency are measured and compared at each stages of processing. The conversion efficiencies enhancing of 17.78%, 27.5% and of 47.85% are obtained as the solar cell with indium nanoparticles on a 10-nm, a 30-nm and a 59.5-nm thick TiO2 space layer, respectively, compared to the solar cell without coated a TiO2 layer. Furthermore, the plasmonics conversion efficiency depend on the thickness of space layer are also demonstrated that the increasing by 15.46%, 12.1% and 6.08% for the solar cells with a 10-nm, 30-nm and 59.5-nm thick TiO2 space layer, respectively, were obtained.

This study examines using sub-wavelength surface structure (SWS) anti-reflection (AR) coating with a broad wavelength range of low reflectance and wide-acceptance angles of incident light fabricated on solar cells for improving solar cell performance. The SWS AR coating consisted of TiO 2 and SiO 2 layers that had thicknesses of a quarter-wavelength and heights of 300-nm SiO 2 nano-pillars on the top surface of the sub-wavelength structure. The sub-wavelength SiO 2 nano-pillars were formed using a reactive ion etching process with CF 4 that involved using silver nanoparticles as the etching masks. The reflective spectrum of the SWS AR coating was examined using software simulation and experimental measurement. The average reduced reflectance of SWS AR coating was less than 3% between 450 nm and 900 nm wavelengths. SWS AR coating improved solar cell performance in conversion efficiency and maximal output power (P MAX ) at higher incident angle illumination. Therefore, at an incident angle of 60°, the conversion efficiency improvement was 52.9% and the P MAX was 55.8%, as compared with the cells that had two layers (TiO 2 /SiO 2 ) of AR coating.

This paper reports impressive improvements in the optical and electrical performance of metal-oxide-semiconductor (MOS)-structure silicon solar cells through the incorporation of plasmonic indium nanoparticles (In-NPs) and an indium-tin-oxide (ITO) electrode with periodic holes (perforations) under applied bias voltage. Samples were prepared using a plain ITO electrode or perforated ITO electrode with and without In-NPs. The samples were characterized according to optical reflectance, dark current voltage, induced capacitance voltage, external quantum efficiency, and photovoltaic current voltage. Our results indicate that induced capacitance voltage and photovoltaic current voltage both depend on bias voltage, regardless of the type of ITO electrode. Under a bias voltage of 4.0 V, MOS cells with perforated ITO and plain ITO, respectively, presented conversion efficiencies of 17.53% and 15.80%. Under a bias voltage of 4.0 V, the inclusion of In-NPs increased the efficiency of cells with perforated ITO and plain ITO to 17.80% and 16.87%, respectively.

In this study, the optical generation rate and surface recombination velocity (SRV) of the emitter layer of a thin-film silicon solar cell, which depend on the depth, width, and number of nano-holes on the cell’s surface, were simulated and investigated. The trade-off between the optical generation rate and SRV was examined in terms of short-circuit current density (J sc ), open-circuit voltage (V oc ), and conversion efficiency (η) using a two-step simulation. The simulated results indicated that a thin-film solar cell with a proper nano-hole structure on the emitter layer can be used to achieve much higher J sc and η performances.

The paper experimentally demonstrated the optical frequency quadrupling microwave signal generation, a 4 GHz radio frequency (RF) signals up-conversion to 16 GHz in a radio over fiber (ROF) link, using twice optical carrier suppression modulation. The RF signal was mixed with 1.25 Gbps NRZ-OOK data firstly and then modulated by two cascaded single-electrode optical intensity modulators. The obtained 1.25 Gbps/16 GHz ROF signal was transmitted and characterized in the optical fiber link. At BER of 10−9, low power penalty of 1.0 and 1.4 dB were obtained over a fiber link with a transmission distance of 25 and 50 km.

In this paper, we experimentally demonstrated the 1550 nm short optical pulses generation using a TO-packaged gain-switching distributed feedback (DFB) semiconductor laser driving by 2.5 GHz radio frequency (RF) signals and combining with optical injection techniques. The characteristics of the generated optical pulse by the proposed CW-mode external-injection and pulse-mode self-injection schemes are characterized in the side mode suppression ratio (SMSR), spectrum line-width, pulse-width and root-meansquare (RMS) jitter. In the CW-mode external-injection case, the SMSR of 35.5 dB, line-width of 0.235 nm, pulse-width of 47.69 ps, and RMS jitter of 1.4 ps are obtained when the optical injection ratio of 5 dB. In the pulse-mode self-injection, however, the SMSR of 61.2 dB, spectrum line-width of 0.189 nm, pulse-width of 58.46 ps, and RMS jitter of 1 ps are achieved and its overall performances are better than CW-mode externalinjection one.

This paper presents fabrication and characterization of InP-based separate absorp- tion, grading, charge, and InP/InAlAs hetro-multiplication (SAGCM) single photon avalanche photo-detectors (SPADs) for application of single photon flber optic communications. The dark current (ID) of SPAD at 90% of the breakdown voltage (VBR) was 37.8pA and 18.8nA at 200K and 300K, respectively. Under i40 - C and gate repetition frequency of 10kHz with pulse width of 2ns, the performance of dark count probability Pdc = 0:02, single-photon detection e-ciency ·det = 11:5%, noise equivalent power NEP = 5£10 i14 W/(Hz) 1=2 , a factor of quantum bit-error rate of Pdc=·det = 0:16 were simultaneously achieved. In addition, both the dark current and the dark count exhibited activation energy of 0.24eV in temperature below 240K which shown the dominant generation sources were band-to-band tunneling and fleld-enhanced band-traps-band tunneling.

A radio-on-hybrid wavelength-division-multiplexing (WDM) transport system employing mutually injection-locked Fabry–Perot laser diodes (F–P LDs) is proposed and demonstrated. System performances evaluated by carrier to noise ratio (CNR), composite second order (CSO), composite triple beat (CTB), bit error rate (BER), and third-order intermodulation distortion to carrier ratio (IMD 3 /C) for simultaneous transmission of CATV/LAN/ITS are improved. Our proposed systems are relatively simple and potentially low cost due to the use of mutually injection-locked F–P LDs as broadband light source (BLS).

A radio-on-dense-wavelength-division-multiplexing (DWDM) transport system based on injection-locked Fabry-Perot laser diodes (FP LDs) with four microwave carriers and large effective area fiber (LEAF) transmission was proposed and demonstrated. Good performance of bit error rate (BER) and intermodulation distortion to carrier ratio (IMD/C) over a-50km of LEAF was obtained. Signal quality meets the demands of personal handy system (PHS)/vehicle information and communication system (VICS)/electronic toll collection (ETC)/satellite broadcasting (SB).

The optical generation rate and surface recombination velocity (SRV) increasing with the created nano-holes depth, width, and number on the emitter layer of a thin-film silicon solar cell are studied. The trade-off between the optical generation rate and surface recombination velocity was exhibit in short-circuit current density (J sc ), Open-circuit voltage (V oc ), and conversion efficiency (η) using a two-step simulation. The simulated results indicated that a thin-film solar cell with a proper nano-holes structure on the emitter layer can be achieved a much high J sc and η performances.

Electrical and optical performance of crystalline silicon solar cells with down shifting Eu-doped silicate phosphors film using spin-on film technique was experimental demonstrated. The coverage of phosphors particles was controlled using the deposition holding time by spin-on process. Photo-luminescence (PL) and external quantum efficiency (EQE) response of the cells with Eu-doped silicate phosphors are used to examine the effectiveness of the phosphors down shifting. An impressive enhanced in conversion efficiency of 19.7% was obtained when the cell with a 5 wt% Eu-doped silicate phosphors mixing with SiO2 solution for a 5 s deposition holding time.

Performance enhancement of the p-n junction silicon solar cells with ITO/Al 2 O 3 /TiO 2 antireflective coating is experimentally demonstrated. The reflectivity of the ITO/Al 2 O 3 /TiO 2 layer configuration with various thicknesses on Si wafer are simulated and characterized. Optical reflection and external quantum efficiency of the proposed MOS-structure Si solar cells are measured and compared with the changing in oxide-film thickness. An impressive efficiency enhancement of 42.39 % was obtained for the cell consisted of a 50-nm-ITO/5-nm-Al 2 O 3 /25-nm-TiO 2 antireflection coating, compared to the reference cells.

Impressive efficiency enhancement of 15.38% of crystalline-silicon solar-cell with Eu-doped silicate-phosphors and SiO 2 -layer using spin-on technique is demonstrated. Reflectance, external quantum efficiency, and photovoltaic I-V characteristics are used to examine the downshifting effectiveness.

In this article, we demonstrated the fabrication of high-speed 1.55-μm ridge-waveguide semiconductor laser diodes (LDs) by a called “self-terminated oxide polish (STOP)” planarization technique. This technique can effectively reduce the parasitic parameters and improve the device performance. In addition, it can also lower the cost of device fabrication. The LDs with a 4-μm ridge based on the STOP process exhibit a threshold current of 22 mA at 20 °C, a light output power of 16 mW at 100 mA and 20 °C, and a characteristic temperature of 80.6 K from −10 to 80 °C. The device can be directly modulated at −3 dB bandwidth in excess of 11 and 14.5 GHz at 50 and 100 mA, respectively.

We propose to include a Bragg-wavelength-detuned (BWD) layer in a portion of the cavity of an index-coupled distributed feedback (DFB) laser to overcome the mode degeneracy problem. The new two-section DFB (TSDFB) lasers are experimentally demonstrated to have comparable device dimension and output characteristics as conventional DFB lasers but have much better spectral stability. High side-mode suppression ratio can be obtained over a wide range of current injection and temperature conditions when the laser is coated with anti-reflection coatings on both output facets. Wavelength tuning over 5.4 nm can be obtained by adjusting the heatsink temperature and levering the bias currents. With excellent mode stability, the TSDFB lasers are demonstrated to perform wavelength conversion with large extinction ratio, high conversion efficiency, and waveform reshaping capability. The wavelength conversion can cover 30-THz of input frequency that matches the frequency grid of the dense wavelength division multiplexing systems. Penalty-free conversion is also demonstrated.

In this letter, we report on an alternative method to fabricate a high-efficiency planar-type oxide-confined 850-nm vertical-cavity surface-emitting lasers (VCSELs). The planarized process of VCSELs was to use the silicon oxide as the buried layer. As a result, these devices with an oxidized aperture of 3 /spl mu/m in diameter exhibit a single-transverse mode behavior throughout the operation current range. In addition, the static characteristics of VCSELs at 300 K include a threshold current of 0.52mA corresponding to a threshold voltage of 2.2 V, a maximum single transverse-mode light output power of 1.13 mW at 4.5 mA, and an external differential quantum efficiency of 35%. On the other hand, this TO-packaged planar-type 850-nm VCSEL for back-to-back test shows a wide open along with symmetric eye diagram and could also pass the 10 Gb/s mask as operating at 10.3 Gb/s and 4 mA. Furthermore, the VCSEL can still keep the eye diagram open and symmetric after the 66-m multi-mode fiber transmission and has a power penalty of 6.6 dB because of fiber dispersion for 10.3 Gb/s data rate at a bit error rate of 10/sup -11/. These results confirm the excellent high-speed performance of SiO/sub x/-planarized VCSELs as compared to the polyimide-planarized VCSELs.

We have successfully fabricated InGaAs edge-coupled photodiodes (EC-PDs) with a light funnel integrated (LIFI) in front of the coupling aperture, called LIFI EC-PD, based on the self-terminated oxide polish (STOP), the crystallographic slope etching of InP, and the self-aligned diffusion (SAD) techniques. The LIFI EC-PD presents not only a lower dark current density (/spl sim/ 4.4 mA/cm/sup 2/) but also a higher responsivity (/spl sim/ 0.4 A/W) than that of the mesa EC-PD (27 mA/cm/sup 2/ and 0.26 A/W, respectively). Furthermore, the thick oxide film serves as the funnel in front of active-region aperture to enhance the coupling efficiency and to lower the bonding pad capacitance down to 50 fF. The lowered bonding pad capacitance can be beneficial in designing a device with a higher transit-time-limited frequency response of beyond 30 GHz. The LIFI EC-PD with a 1-/spl mu/m thick absorption layer exhibits a 3-dB bandwidth of 20 GHz and a responsivity of /spl sim/ 0.4 A/W.

1.3 μm compressive-strain multiple-quantum-well (CS-MQW) GaInAsP/GaInAsP laser diodes (LDs) with a tensile-strain GaInP electron stopper layer (TS-ESL) were grown by metalorganic chemical vapor deposition (MOCVD). The TS-ESL, which is inserted between the MQW region and p-side separate-confinement-heterostructure (SCH) layer, is used to suppress the electron overflow from MQW region to p-side SCH layer and to compensate the strain resulted from the CS-MQW region. The fabricated 3.5-μm-ridge-width LDs with a GaInP ESL exhibit a lower threshold current density of 0.88 kA/cm2, a higher differential quantum efficiency of 48%, a comparable characteristic temperature of 57 K, a maximum operating temperature up to 85 °C, and a red-shift rate of 0.28 nm/°C, as compared to those without a GaInP ESL.

The effect is investigated of introducing a linearly graded-index separate-confinement-heterostructure InGaAsP intermediate layer between the InGaAs cap layer and the InP cladding layer to improve the characteristics of 1.3 μm AlGaInAs strain-compensated multiple-quantum-well laser diodes (LDs). With the InGaAsP intermediate layer, 3 μm-ridge-strip LDs without facet coating under CW operation exhibit a threshold current of 16 mA, a resistance of 5.8 Ω, a characteristic temperature of 75 K in the range 20–70°C and 41 K at 70–100°C, a differential quantum efficiency of 50% and a low slope efficiency drop of −1.3 dB between 20 and 70°C. These characteristics are better than those of LDs without the InGaAsP intermediate layer. A wavelength swing of 0.48 nm/°C for LDs operated at 50 mA is achieved.