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Hot wall epitaxy(HWE)법에 의한 $ZnIn_{2}Se_{4}$ 단결정 박막 성장과 가전자대 갈라짐에 대한 광전류 연구
홍광준,Hong, Kwang-Joon 한국결정성장학회 2008 韓國結晶成長學會誌 Vol.18 No.5
A stoichiometric mixture of evaporating materials for $ZnIn_2Se_4$ single crystal thin films was prepared from horizontal electric furnace. To obtain the single crystal thin films, $ZnIn_2Se_4$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the Hot Wall Epitaxy (HWE) system. The source and substrate temperatures were $630^{\circ}C$ and $400^{\circ}C$, respectively. The crystalline structure of the single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of $ZnIn_2Se_4$ single crystal thin films measured from Hall effect by van der Pauw method are $9.41\times10^{16}cm^{-3}$ and $292cm^2/v{\cdot}s$ at 293 K, respectively. The temperature dependence of the energy band gap of the $ZnIn_2Se_4$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)=1.8622eV-(5.23\times10^{-4}eV/K)T^2/(T+775.5K)$. The crystal field and the spin-orbit splitting energies for the valence band of the $ZnIn_2Se_4$ have been estimated to be 182.7 meV and 42.6 meV, respectively, by means of the photocurrent spectra and the Hopfield quasicubic model. These results indicate that the splitting of the ${\Delta}so$ definitely exists in the ${\Gamma}_5$ states of the valence band of the $ZnIn_2Se_4/GaAs$ epilayer. The three photo current peaks observed at 10 K are ascribed to the $A_{1}-$, $B_{1}-exciton$ for n = 1 and $C_{27}-exciton$ peaks for n = 27. 수평 전기로에서 $ZnIn_2Se_4$ 단결정을 합성하여 HWE(Hot Wall Epitaxy)방법으로 $ZnIn_2Se_4$ 단결정 박막을 반절연성 GaAs(100) 기판에 성장시켰다. $ZnIn_2Se_4$ 단결정 박막의 성장 조건을 증발원의 온도 $630^{\circ}C$, 기판의 온도 $400^{\circ}C$였고 성장 속도는 0.5 $\mu m/hr$였다. $ZnIn_2Se_4$ 단결정 박막의 결정성의 조사에서 10K에서 광발광(photoluminescence) 스펙트럼이 682.7nm ($1.816{\underline{1}}eV$)에서 exciton emission 스펙트럼이 가장 강하게 나타났으며, 또한 이중결정 X-선 요통곡선(DCRC)의 반폭치(FWHM)도 128 arcsec로 가장 작아 최적 성장 조건임을 알 수 있었다. Hall 효과는 van der Pauw 방법에 의해 측정되었으며, 온도에 의존하는 운반자 농노와 이동도는 293 K에서 각각 $9.41\times10^{16}/cm^{-3}$, $292cm^2/V{\cdot}s$였다. $ZnIn_2Se_4$/SI(Semi-Insulated) GaAs(100) 단결정 박막의 광흡수와 광전류 spectra를 293 K에서 10K까지 측정하였다. 광흡수 스펙트럼으로부터 band gap $E_g(T)$는 varshni공식에 따라 계산한 결과 $E_g(T)=1.8622\;eV-(5.23\times10^{-4}eV/K)T^2/(T+775.5K)$ 이었으며 광전류 스펙트럼으로부터 Hamilton matrix(Hopfield quasicubic mode)법으로 계산한 결과 crystal field splitting energy ${\Delta}cr$값이 182.7meV이며 spin-orbit energy ${\Delta} so$값은 42.6meV임을 확인하였다. 10 K일 때 광전류 봉우리들은 n= 1, 27일때 $A_{1}-$, $B_{1}-$와 $C_{27}-exciton$ 봉우리임을 알았다.
펄스 레이저 증착(PLD)법에 의한 ZnO 박막 성장과 가전자대 갈라짐에 대한 광전류 연구
홍광준 ( Kwang Joon Hong ) 한국센서학회 2005 센서학회지 Vol.14 No.3
N/A ZnO epilayer were synthesized by the pulesd laser deposition(PLD) process on Al₂O₃ substrate after irradiating the surface of the ZnO sintered pellet by the ArF(l93 nm) excimer laser. The epilayers of ZnO were achieved on sapphire (Al₂O₃) substrate at a temperature of 400 ℃. The crystalline structure of epilayer was investigated by the photoluminescence. The carrier density and mobility of ZnO epilayer measured with Hall effect by van der Pauw method are 8.27 x 1016 cm^(-3) and 299 cm²N s at 293 K, respectively. The temperature dependence of the energy band gap of the ZnO obtained from the absorption spectra was well described by the Varshni`s relation, E5(T) = 3.3973 eV - (2.69 x 10^(-4) eV/ K)T²/(T + 463 K). The crystal field and the spin-orbit splitting energies for the valence band of the ZnO have been estimated to be 0.0041 eV and 0.0399 eV at 10 K, respectively, by means of the photocurrent spectra and the Hopfield quasicubic model. These results indicate that the splitting of the Aso definitely exists in the F6 states of the valence band of the ZnO. The three photocurrent peaks observed at 10 K are ascribed to the A_(1-), B_(1-), and C_(1-)exciton peaks for n = 1.
태양 전지용 $CuGaSe_2$ 단결정 박막 성장과 태양전지로의 응용
윤석진,홍광준,Yun, Suk-Jin,Hong, Kwang-Joon 한국결정성장학회 2005 한국결정성장학회지 Vol.15 No.6
[ $CuGaSe_2$ ] 단결정 박막은 수평 전기로에서 합성한 $CuGaSe_2$ 다결정을 증발원으로하여, hot wall epitaxy(HWE) 방법으로 증발원과 기판(반절연성 GaAs(100))의 온도를 각각 $610^{\circ}C,\;450^{\circ}C$로 고정하여 단결정 박막을 성장하였다. 이때 단결정 박막의 결정성은 광발광 스펙트럼(PL)과 이중결정 X-선 요동곡선 (DCRC)으로부터 구하였다. Hall 효과는 Van der Pauw 방법에 의해 측정되었으며, 293 K에서 운반자 농도와 이동도는 각각 $4.87{\times}10^{17}/cm^3,\;129cm^2/V{\cdot}s$였다. $n-Cds/p-CuGaSe_2$ 합 태양전지에 $80mW/cm^2$의 광을 조사시켜 최대 출력점에서 전압은 0.41 V, 전류밀도는 $21.8mA/cm^2$였고, fill factor는 0.75 그리고 태양전지 전력변환 효율은 11.17% 였다. Single crystal $CuGaSe_2$ layers were grown on thoroughly etched semi-insulating CaAs(100) substrate at $450^{\circ}C$ with hot wall epitaxy (HWE) system by evaporating $CuGaSe_2$ source at $610^{\circ}C$. The crystalline structure of the single crystal thin films was investigated by the photoluminescence (PL) and double crystal X-ray diffraction (DCXD). The carrier density and mobility of single crystal $CuGaSe_2$ thin films measured with Hall effect by Van der Pauw method are $4.87{\times}10^{17}cm^{-3}$ and $129cm^2/V{\cdot}s$ at 293 K, respectively. The temperature dependence of the energy band gap of the $CuGaSe_2$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)=1.7998eV-(8.7489{\times}10^{-4}eV/K)T^2/(T+335K)$. The voltage, current density of maxiumun power, fill factor, and conversion, efficiency of $n-CdS/p-CuGaSe_2$, heterojunction solar cells under $80mW/cm^2$ illumination were found to be 0.41 V, $21.8mA/cm^2$, 0.75 and 11.17%, respectively.
Hot Wall epitaxy(HWE)법에 의한 $CdGa_2Se_4$ 단결정 박막의 성장과 가전자대 갈라짐에 대한 광전류 연구
박창선,홍광준,Park, Chang-Sun,Hong, Kwang-Joon 한국결정성장학회 2007 韓國結晶成長學會誌 Vol.17 No.5
[ $CdGa_2Se_4$ ] 단결정 박막을 수평 전기로에서 합성한 $CdGa_2Se_4$ 다결정을 증발원으로하여, hot wall epitaxy(HWE) 방법으로 증발원과 기판(반절연성-GaAs(100))의 온도를 각각 $630^{\circ}C,\;420^{\circ}C$로 고정하여 성장하였다. 이때 단결정 박막의 결정성은 광발광 스펙트럼과 이중결정 X-선 요동곡선(DCRC)으로 부터 구하였다. Hall 효과는 van der Pauw 방법에 의해 측정되었으며, 293K에서 운반자 농도와 이동도는 각각 $8.27{\times}10^{17}cm^{-3},\;345cm^2/V{\cdot}s$였다. $CdGa_2Se_4/SI$(Semi-Insulated) GaAs(100) 단결정 박막의 광흡수와 광전류 spectra를 293K에서 10K까지 측정하였다. 광흡수 스펙트럼으로부터 band gap $E_g(T)$는 Varshni 공식에 따라 계산한 결과 $E_g(T)=2.6400eV-(7.721{\times}10^{-4}eV/K)T^2/(T+399K)$였다. 광전류 스펙트럼으로부터 Hamilton matrix(Hopfield quasicubic mode)법으로 계산한 결과 crystal field splitting 에너지 ${\Delta}cr$값이 106.5meV이며 spinorbit 에너지 ${\Delta}so$값은 418.9meV임을 확인하였다. 10K일 때 광전류 세 봉우리들은 $A_{1^-},\;B_{1^-}$와 $C_{11}-exciton$ 봉우리임을 알았다. Single crystal $CdGa_2Se_4$ layers were grown on a thoroughly etched semi-insulating GaAs(100) substrate at $420^{\circ}C$ with the hot wall epitaxy(HWE) system by evaporating the polycrystal source of $CdGa_2Se_4$ at $630^{\circ}C$. The crystalline structure of the single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction(DCXD). The carrier density and mobility of single crystal $CdGa_2Se_4$ thin films measured with Hall effect by van der Pauw method are $8.27{\times}10^{17}cm^{-3},\;345cm^2/V{\cdot}s$ at 293 K, respectively. The photocurrent and the absorption spectra of $CdGa_2Se_4/SI$(Semi-Insulated) GaAs(100) are measured ranging from 293 K to 10 K. The temperature dependence of the energy band gap of the $CdGa_2Se_4$ obtained from the absorption spectra was well described by the Varshni's relation $E_g(T)=2.6400eV-(7.721{\times}10^{-4}eV/K)T^2/(T+399K)$. Using the photocurrent spectra and the Hopfield quasicubic model, the crystal field energy(${\Delta}cr$) and the spin-orbit splitting energy(${\Delta}so$) far the valence band of the $CdGa_2Se_4$ have been estimated to be 106.5 meV and 418.9 meV at 10 K, respectively. The three photocurrent peaks observed at 10 K are ascribed to the $A_{1^-},\;B_{1^-},\;and\;C_{11}-exciton$ peaks.