• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1216-1219
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• 1994

A reflection type SEED from LP-MOCVD grown InGaAs/GaAs ESQW structures, with 5% In fraction, has been fabricated and its basic characteristics were investigated. Its intrinsic region consists of 50 pairs of alternating $100{\AA}$ $In_{0.05}Ga_{0.95}As$ barrier and $100{\AA}$ GaAs layers. And a multilayer reflector stack of $Al_{0.12}Ga_{0.88}As(641{\AA})-/AlAs(774{\AA})$ was vertically integrated below the p-i-n structures. The device processing includes the mesa etching, insulator deposition, indium metallization, and thermal alloy for Ohmic contact. Photocurrent spectrum measurement showed the exciton absorption peak at 905nm and availability as a optical switching device. This device showed a contrast ratio of 2:1 by the reflectance spectrum measurement.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.1
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• pp.123-126
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• 2010

$Cu_2O$ nanoparticles-based films are fabricated by spin-coating on glass substrates and their optoelectronic characteristics are investigated in this study. The $Cu_2O$ films are nearly all-transparent as high as 98% in a wavelength range from 400 nm to 900 nm and three exciton peaks associated with the sublevels in the conduction band are observed at the wavelengths shorter than 400 nm in the absorption spectrum. Under the illumination of the 325 nm wavelength light, the photocurrent efficiency of the $Cu_2O$ film is $1.8\times10^5 {\mu}A/W$ at a voltage of 2.5 V in air.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.05a
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• pp.59-62
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• 1994

Tact Electrical conductivity. optical absorption spectra of poly(p-phenylene vinylene) and their dependence on stretching are discussed in detail. The conductivity in the parallel direction to the stretching is higher over one order in magnitude than that in the perpendicular direction to the stretching is higher over one order in magnitude than that in the perpendicular direction to the stretching. The photocurrent spectrum for the ligh polarized parallel to the chain direction is much enhanced in lower photon energy compared with that for the light polarized perpendicular to that direction. The result may be originated in the difference of energies which is needed to photogenerate carriers wi th the light polarized parallel and perpendicular to the chain stretched direction.

• Korean Journal of Materials Research
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• v.32 no.8
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• pp.333-338
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• 2022

In this work, we developed silver nanowires and a silicon based Schottky junction and demonstrated ultrafast broadband photosensing behavior. The current device had a response speed that was ultrafast, with a rising time of 36 ㎲ and a falling time of 382 ㎲, and it had a high level of repeatability across a broad spectrum of wavelengths (λ = 365 to 940 nm). Furthermore, it exhibited excellent responsivity of 60 mA/W and a significant detectivity of 3.5 × 10¹² Jones at a λ = 940 nm with an intensity of 0.2 mW cm^-2 under zero bias operating voltage, which reflects a boost of 50 %, by using the AC PV effect. This excellent broadband performance was caused by the photon-induced alternative photocurrent effect, which changed the way the optoelectronics work. This innovative approach will open a second door to the potential design of a broadband ultrafast device for use in cutting-edge optoelectronics.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.6
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• pp.445-454
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• 2001

The stochiometric mix of evaporating materials for the CuInSe$_2$ single crystal thin films was prepared from horizontal furnace. To obtain the single crystal thin films, CuInSe$_2$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the Hot Wall Epitaxy(HWE) system. The source and substrate temperature were 62$0^{\circ}C$ and 41$0^{\circ}C$, respectively. The crystalline structure of single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of CuInSe$_2$ single crystal thin films measured from Hall effect fby van der Pauw method are 9.62x10$^{16}$ cm$^{-3}$ , 296$\textrm{cm}^2$/V.s at 293 K, respectively. From the photocurrent spectrum by illumination of perpendicular light on the c-axis of the CuInSe$_2$ single crystal thin film we have found that he values of spin orbit splitting ΔSo and the crystal field splitting ΔCr were 6.1 meV and 175.2 meV at 10K, respectively. From the photoluminescence measurement on CuInSe$_2$ single crystal thin film we observed free excition (Ex) existing only high quality crystal and neutral bound exiciton (D$^{\circ}$,X) having very strong peak intensity. Then, the full-width-at-half-maximum(FWHM) and binding energy of neutral donor bound excition were 7meV and 5.9meV, respectivity. by Haynes rule, an activation energy of impurity was 50 meV.

• Advances in nano research
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• v.3 no.3
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• pp.133-141
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• 2015

Influence of Ag nanoparticles on optical and photovoltaic properties of, silicon substrates, silicon solar cells and glass have been investigated. Silver nanoparticles have been fabricated by evaporation of thin Ag layers followed by the thermal annealing. The surface plasmon resonance peak was observed in the absorbance spectrum at 470 nm of glass with deposited silver nanoparticles. It is demonstrated that deposition of silver nanoparticles on silicon substrates was accompanied with a significant decrease in reflectance at the wavelength 360-1100 nm and increase of the absorption at wavelengths close to the band gap for Si substrates. We studied influence of Ag nanoparticles on photovoltaic characteristics of silicon solar cells without and with common use antireflection coating (ARC). It is shown that silver nanoparticles deposited onto the front surface of the solar cells without ARC led to increase in the photocurrent density by 39% comparing to cells without Ag nanoparticles. Contrary to this, solar cells with Ag nanoparticles deposited on front surface with ARC discovered decrease in photocurrent density. The improved performance of investigated cells was attributed to Ag-plasmonic excitations that reduce the reflectance from the silicon surface and ultimately leads to the enhanced light absorption in the cell. This study showed possibility of application of Ag nanoparticles for the improvement of the conversion efficiency of waferbased silicon solar cells instead of usual ARC.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.266-272
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• 2002

The stochiometric mixture of evaporating materials for the ZnIn$_2$S$_4$ single crystal thin film was prepared from horizontal furnace. To obtain the ZnIn$_2$S$_4$ single crystal thin film, ZnIn$_2$S$_4$ mixed crystal was deposited on throughly etched semi-insulating GaAs(100) in the Hot Wall Epitaxy(HWE) system. The source and substrate temperature were 610 $^{\circ}C$ and 450 $^{\circ}C$, respectively and the growth rate of the ZnIn$_2$S$_4$ single crystal thin film was about 0.5 $\mu\textrm{m}$/hr. The crystalline structure of ZnIn$_2$S$_4$ single crystal thin film was investigated by photo1uminescence and double crystal X-ray diffraction(DCXD) measurement. The carrier density and mobility of ZnIn$_2$S$_4$ single crystal thin film measured from Hall effect by van der Pauw method are 8.51${\times}$10$\^$17/ cm$\^$-3/, 291 $\textrm{cm}^2$/V$.$s at 293 $^{\circ}$K, respectively. From the photocurrent spectrum by illumination of perpendicular light on the c - axis of the ZnIn$_2$S$_4$ single crystal thin film, we have found that the values of spin orbit splitting ΔSo and the crystal field splitting ΔCr were 0.0148 eV and 0.1678 eV at 10 $^{\circ}$K, respectively. From the photoluminescence measurement of ZnIn$_2$S$_4$ single crystal thin film, we observed free excition (E$\_$X/) typically observed only in high quality crystal and neutral donor bound exciton (D$^{\circ}$,X) having very strong peak intensity. The full width at half maximum and binding energy of neutral donor bound excition were 9 meV and 26 meV, respectively. The activation energy of impurity measured by Haynes rule was 130 meV.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.273-280
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• 2002

The stochiometric mix of evaporating materials for the CuGaTe$_2$ single crystal thin films was prepared from horizontal furnance. For extrapolation method of X-ray diffraction patterns for the CuGaTe$_2$ polycrystal, it was found tetragonal structure whose lattice constant a$\_$0/ and c$\_$0/ were 6.025 ${\AA}$ and 11.931 ${\AA}$, respectively. To obtain the single crystal thin films, CuGaTe$_2$ mixed crystal was deposited on throughly etched semi-insulator GaAs(100) substrate by the Hot Wall Epitaxy (HWE) system. The source and substrate temperature were 670 $^{\circ}C$ and 410 $^{\circ}C$ respective1y, and the thickness of the single crystal thin films is 2.1 $\mu\textrm{m}$. The crystalline structure of single crystalthin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). Hall effect on this sample was measured by the method of van der Pauw and studied on carrier density and mobility dependence on temperature. The carrier density and mobility of CuGaTe$_2$ single crystal thin films deduced from Hall data are 8.72${\times}$10$\^$23/㎥, 3.42${\times}$10$\^$-2/㎡/V$.$s at 293K, respectively. From the photocurrent spectrum by illumination of perpendicular light on the c - axis of the CuGaTe$_2$ single crystal thin film, we have found that the values of spin orbit coupling Δs.o and the crystal field splitting Δcr were 0.0791 eV and 0/2463eV at 10K, respectively. From the PL spectra at 10K, the peaks corresponding to free bound excitons and D-A pair and a broad emission band due to SA is identified. The binding energy of the free excitons are determined to be 0.0470eV and the dissipation energy of the donor -bound exciton and acceptor-bound exciton to be 0.0490eV, 0.00558eV, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.171-174
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• 2004

The stochiometric $AgGaSe_2$ polycrystalline mixture of evaporating materials for the $AgGaSe_2$ single crystal thin film was prepared from horizontal furnace. To obtain the single crystal thin films, $AgGaSe_2$ mixed crystal and semi-insulating GaAs(100) wafer were used as source material and substrate for the Hot Wall Epitaxy (HWE) system, respectively. The source and substrate temperature were fixed at $630^{\circ}C$ and $420^{\circ}C$, respectively. The thickness of grown single crystal thin films is $2.1{\mu}m$. The single crystal thin films were investigated by photoluminescence and double crystal X-ray diffraction(DCXD) measurement. The carrier density and mobility of $AgGaSe_2$ single crystal thin films measured from Hall effect by van der Pauw method are $4.89{\times}10^{17}\;cm^{-3},\;129cm^2/V{\cdot}s$ at 293K, respectively. From the photocurrent spectrum by illumination of perpendicular light on the c - axis of the $AgGaSe_2$ single crystal thin film, we have found that the values of spin orbit splitting ${\Delta}S_o$ and the crystal field splitting ${\Delta}C_r$ were 0.1762 eV and 0.2494 eV at 10 K, respectively. From the photoluminescence measurement of $AgGaSe_2$ single crystal thin film, we observed free excition $(E_X)$ observable only in high quality crystal and neutral bound exciton $(D^o,X)$ having very strong peak intensity And, the full width at half maximum and binding energy of neutral donor bound excition were 8 meV and 14.1 meV, respectively. By Haynes rule, an activation energy of impurity was 141 meV.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.163-166
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• 2001

The stochiometric mix of evaporating materials for the $ZnGa_{2}Se_{4}$ single crystal thin films was prepared from horizontal furnace. To obtain the single crystal thin films, $ZnGa_{2}Se_{4}$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the Hot Wall Epitaxy (HWE) system. The source and substrate temperature were $610^{\circ}C$ and $450^{\circ}C$, respectively. The crystalline structure of single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of $ZnGa_{2}Se_{4}$ single crystal trun films measured from Hall effect by van der Pauw method are $9.63{\times}10^{17}cm^{-3}$, $296cm^{2}/V{\cdot}s$ at 293 K, respectively. From the photocurrent spectrum by illumination of perpendicular light on the c axis of the $ZnGa_{2}Se_{4}$ single crystal thin film, we have found that the values of spin orbit splitting $\Delta$ So and the crystal field splitting $\Delta$Cr were 251.9 meV and 183.2 meV at 10 K, respectively. From the photoluminescence measurement on $ZnGa_{2}Se_{4}$ single crystal thin film, we observed free excition (Ex) existing only high quality crystal and neutral bound exiciton $(A^{0},X)$ having very strong peak intensity. Then, the full-width-at -half-maximum(FWHM) and binding energy of neutral acceptor bound excition were 11 meV and 24.4 meV, respectivity. By Haynes rule, an activation energy of impurity was 122 meV.