• New & Renewable Energy
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• v.5 no.4
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• pp.34-37
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• 2009

Using six SMD(surface mount device) type AlGaAs/GaAs single junction solar cells connected in series, a power source was fabricated for a white GaN LED. The electrical properties of the power source was measured and analyzed under one sun (100mW/$cm^2$) and various indoor light (300 - 900 lux) conditions. Under 600 lux indoor light condition, output power was 17.06 ${\mu}W$ and it was 30.75 ${\mu}W$ under 900 lux indoor light condition. Using the fabricated solar cell power supply, we have turned on the white GaN LED. It was worked well under 15 ${\mu}W$(at 480 lux) power supplied from solar cell array. This kind of solar cell power supply can be used as a power source for ubiquitous sensor network (USN).

• New & Renewable Energy
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• v.5 no.3
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• pp.26-31
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• 2009

Using MBE growth method, GaAs/AlGaAs solar cell structure was grown. Deposited electrodes are Au/Ni/Ge for n-type and Au/Pt/Ti for p-type electrodes were deposited by E-beam evaporator. Indoor light concentrators were devised and fabricated in order to concentrate artificial solar rays. Also mirror and prism and Fresnel lens concentration system with solar simulator were devised and fabricated. Results of solar cell characteristics were measured with shutting system which can control the amount of light. Maximum power density was 2.13 W/$cm^2$ and maximum concentration was 124 sun, when mirror with Fresnel lens was used at $7854\;mm^2$ of shutter hole.

• Journal of the Korean Vacuum Society
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• v.22 no.3
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• pp.162-167
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• 2013

An epitaxial layer structure for heterojunction p-InGaP/N-InAlGaP solar cell has proposed. Simulation for current density-voltage characteristics has been performed on p-InGaP/N-InAlGaP structure and the simulation results were compared with p-InGaP/p-GaAs/N-InAlGaP structure and homogeneous InGaP pn junction structure. The simulation result showed that the maximum output power and fill factor have greatly increased by replacing n-InGaP with N-InAlGaP. The thicknesses of p-InGaP and n-InAlGaP were optimized for the epitaxial layer structure of p-InGaP/N-InAlGaP.

• Current Photovoltaic Research
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• v.5 no.4
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• pp.135-139
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• 2017

We fabricated two different transparent conducting oxide thin films of ZnO doped with Ga ($Ga_2O_3$ 0.9 wt%) as well as Al ($Al_2O_3$ 2.1 wt%) (GAZO) and ZnO doped only with Al ($Al_2O_3$ 3 wt%) (AZO). It was investigated how it affects the moisture resistance of the transparent electrode. In addition, $Cu(In,Ga)Se_2$ thin film solar cells with two transparent oxides as front electrodes were fabricated, and the correlation between humidity resistance of transparent electrodes and device performance of solar cells was examined. When both transparent electrodes were exposed to high temperature distilled water, they showed a rapid increase in sheet resistance and a decrease in the fill factor of the solar cell. However, AZO showed a drastic decrease in efficiency at the beginning of exposure, while GAZO showed that the deterioration of efficiency occurred over a long period of time and that the long term moisture resistance of GAZO was better.

• New & Renewable Energy
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• v.5 no.3
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• pp.22-25
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• 2009

For increasing the output voltage, six SMD(surface mount device) type AlGaAs/GaAs solar cells were connected in series. The electrical properties of the array were measured and compared with one sun (100 mW/$cm^2$) and indoor light (480 lux) conditions. Under one sun condition, output power was 21.57 mW and it was $14.67\;{\mu}W$ under indoor light condition. Under the indoor light condition, the intensity of the light is very low compared to one sun condition. Thus the Voc(open circuit voltage) and Isc (short circuit current) of the sample under indoor light condition decreased very much compared to that of under the one sun condition. This kind of solar cell power supply can be used as a power source for ubiquitous sensor network (USN).

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.4
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• pp.929-934
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• 2010

Improvements in characteristics of a single junction AlGaAs/GaAs solar cell are observed by capping a PMMA lens on it. In order to show the effect of the lens, characteristics of a single junction AlGaAs/GaAs solar cell before and after the lens formation are compared under the one-sun illumination condition ($100mW/cm^2$). Characteristics of the solar cell under very weak illumination condition (about 1200 lux) is also measured with the lighting of a fluorescent desk lamp. About 5% of cell efficiency is improved after the capping of PMMA lens on the single junction AlGaAs solar cell and $83\;{\mu}m/cm^2$ of electrical power was generated with the lighting of a desk lamp.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.28A no.1
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• pp.30-39
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• 1991

The influence of physical parameters (Al mole fraction, thickness, doping concentration) in the window and emitter on the efficiency characteristics of heteroface p-$Al_{x}Ga_{1-x}As/p-GaAs/n-GaAs/n^{+}$-GaAs solar cell is investigated. The maximum efficiency theoretically calculated in this device is obtained when a thickness of the window is in a range of (400-1000))$\AA$and a thickness/doping concentration of the emitter is in a range of (0.5-0.8)$\mu$m/(1-7)${\times}10^{17}cm^{-3}$, respectively. Also is the efficiency improved according to the increase of Al mole fraction in the indirect gap window(0.41${\le}x{\le}1.0$). The optimum designed heteroface cell with an area of 0.165cm$^2$fabricated using MOCVD exhibits an active area conversion efficiency of 17%, having a short circuit current density of 21.2mA/cm\ulcorner an open circuit voltage of 0.94V, and a fill factor of 0.75 under ELH-100mW/cm$^2$illumination.

• Current Photovoltaic Research
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• v.2 no.2
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• pp.73-77
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• 2014

To investigate the effect of metal back-reflective layers (MBLs) on the performance of GaAs solar cells, we fabricated GaAs solar cells on Al and Ag metal layers using the transfer printing technique. We also investigated the effect of MBL texturing on the performance of transfer printed GaAs solar cells. Transfer printed solar cells with MBLs exhibited improved photovoltaic performance compared to solar cells without MBLs due to light trapping. We demonstrated GaAs solar cells with MBLs on a flexible substrate and performed systematic bending tests. All the measured characteristics of solar cells showed little change in performance.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.1
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• pp.46-50
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• 1990

Heteroface AlGaAs/GaAs drift solar cells with an active area conversion efficiency of 15.9% under one sun and AM 1.5 condition have been grown by molecular beam epitaxy(MBE). These drift solar cells have graded doping profiles in the base and emitter regions. The cells have a short circuit current density (Jsc) of 19.00 mA/cm\ulcorner an open circuit voltage(Voc) of 0.93 V, and f fill factor(FF) of 0.78, respectively. Conventional solar cells with fixed doping profiles were also grown by MBE for comparison with the drift solar cells. Even though the fabrication cost of MBE grown solar cell is higher, the expected highest conversion efficiency of the single or multiple cells could compensate for the increased cost, particularly in case of space applications.

• Applied Chemistry for Engineering
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• v.30 no.4
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• pp.499-503
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• 2019

Characteristics of solar cells employing a lattice matched GaInP/GaAs quantum well (QW) structure in a single N-AlGaInP/p-InGaP heterojunction (HJ) were investigated and compared to those of solar cells without QW structure. The epitaxial layers were grown on a p-GaAs substrate with $6^{\circ}$ off the (100) plane toward the <111>A. The heterojunction of solar cell consisted of a 400 nm N-AlGaInP, a 590 nm p-GaInP and 14 periods of a 10 nm GaInP/5 nm GaAs for QW structure and a 800 nm p-GaInP for the HJ structure (control cell). The solar cells were characterized after the anti-reflection coating. The short-circuit current density for $1{\times}1mm^2$ area was $9.61mA/cm^2$ for the solar cell with QW structure while $7.06mA/cm^2$ for HJ control cells. Secondary ion mass spectrometry and external quantum efficiency results suggested that the significant enhancement of $J_{sc}$ and EQE was caused by the suppression of recombination by QW structure.