• 한국자기학회지
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• 제3권1호
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• pp.48-55
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• 1993

광전자분광법 (Photoelectron Spectroscopy : PES)을 이용하여, 차세대 광자기 기록매체로 유망한 Co/Pd 다층박막의 전자구조를 연구하였다. Co/Pd 다층박막의 Co 3d 전자 PES 스펙트럼에서는 페르미 에너지 ($E_{F}$) 근처에 폭이 좁은 피이크가 관찰되었고, 아울러 $E_{F}$로부터 약 2.5 eV 아래에 폭이 넓은 피이크도 관찰되었다. 그 중 $E_{F}$ 근처에 위치한 피이크의 폭은 bulk Co 3d 전자 PES 스펙트럼에서의 피이크폭에 비하여 훨씬 좁았는데, 이러한 차이는 Co 자기모멘트가 Co/Pd 다층박막에서 buik Co 에 비하여 증진되는 현상과 일치한다. 한편 $E_{F}$ 아래 2.5 eV에 의치한 피이크는 Pd의 valence band 구조와 유사함이 발견되었는데, 이는 Co 단층과 Pd 단층간에 상당한 상호작용 (hybridization)이 있음을 나타낸다고 볼 수 있다. Co/Pd 다층박막에 대하여 실험적으로 결정한 Co 3d 전자 Pes 스펙트럼을 국재스핀밀도함수이론을 이용하여 얻은 이론적 전자구조 계산결과와 비교하였다. 이상의 비교에 의하면 밴드이론계산에 의한 Co 3d 밴드폭은 실험과 잘 일치하였으나, PES 스펙트럼에서 관찰되어진 $E_{F}$ 근처의 폭이 좁은 피이크는 밴드이론이 잘 기술하지 못함이 발견되었다.

• 센서학회지
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• 제14권3호
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• pp.160-168
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• 2005

ZnO epilayer were synthesized by the pulesd laser deposition(PLD) process on $Al_{2}O_{3}$ substrate after irradiating the surface of the ZnO sintered pellet by the ArF(193 nm) excimer laser. The epilayers of ZnO were achieved on sapphire ($Al_{2}O_{3}$) substrate at a temperature of $400^{\circ}C$. 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 $8.27{\times}1016cm^{-3}$ and $299cm^{2}/V{\cdot}s$ 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, $E_{g}(T)$=3.3973 eV-($2.69{\times}10^{-4}$ eV/K)$T^{2}$/(T+463K). 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 ${\Delta}so$ definitely exists in the ${\Gamma}_{6}$ 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.

• 센서학회지
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• 제16권6호
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• pp.419-427
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• 2007

Single crystal $ZnIn_{2}S_{4}$ layers were grown on a thoroughly etched semi-insulating GaAs(100) substrate at $450^{\circ}C$ with the hot wall epitaxy (HWE) system by evaporating the polycrystal source of $ZnIn_{2}S_{4}$ at $610^{\circ}C$ prepared from horizontal electric furnace. 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 $ZnIn_{2}S_{4}$ thin films measured with Hall effect by van der Pauw method are $8.51{\times}10^{17}\;electron/cm^{-3}$, $291{\;}cm^{2}/v-s$ at 293 K, respectively. The photocurrent and the absorption spectra of $ZnIn_{2}S_{4}$/SI(Semi-Insulated) GaAs(100) are measured ranging from 293 K to 10 K. The temperature dependence of the energy band gap of the $ZnIn_{2}S_{4}$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)$=2.9514 eV. ($7.24{\times}10^{-4}\;eV/K$)$T^{2}$/(T+489 K). Using the photocurrent spectra and the Hopfield quasicubic model, the crystal field energy(${\Delta}cr$) and the spin-orbit splitting energy(${\Delta}so$) for the valence band of the $ZnIn_{2}S_{4}$ have been estimated to be 167.8 meV and 14.8 meV at 10 K, respectively. The three photocurrent peaks observed at 10 K are ascribed to the $A_{1}$-, $B_{1}$-, and $C_{41}$-exciton peaks.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.179-180
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• 2007

Single crystal $AgGaSe_2$ layers were grown on thoroughly etched semi-insulating GaAs(100) substrate at $420^{\circ}C$ with hot wall epitaxy (HWE) system by evaporating $AgGaSe_2$ source 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 $AgGaSe_2$ thin films measured with Hall effect by van der Pauw method are $4.05{\times}\;10^{16}/cm^3$, $139\;cm^2/V{\cdot}s$ at 293 K. respectively. The temperature dependence of the energy band gap of the $AgGaSe_2$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)=1.9501\;eV\;-\;(8.79{\times}10^{-4}\;eV/K)T^2$/(T + 250 K). The crystal field and the spin-orbit splitting energies for the valence band of the $AgGaSe_2$ have been estimated to be 0.3132 eV and 0.3725 eV at 10 K, respectively, by means of the phcitocurrent 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 $AgGaSe_2$. The three photocurrent peaks observed at 10 K are ascribed to the $A_1$-, $B_1$-, and $C_1$-exciton peaks for n = 1.

• 한국결정성장학회지
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• 제14권6호
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• pp.244-252
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• 2004

$CuISe_2$ 단결정 박막은 수평 전기로에서 합성한 $CuInSe_2$ 다결정을 증발원으로하여, hot wall epitaxy(HWE) 방법으로 증발원과 기판(반절연성-GaAs(100))의 온도를 각각 $620^{\circ}C$, $410^{\circ}C$로 고정하여 단결정 박막을 성장하였다. 이때 단결정 박막의 결정성은 광발광 스펙트럼과 이중결정 선 요동곡선(DCRC) 으로 부터 구하였다. Hall 효과는 van der Pauw 방법에 의해 측정되었으며, 293K에서 운반자 농도와 이동도는 각각 $9.62\times10^{16}/\textrm{cm}^3$, 296 $\textrm{cm}^2$/Vㆍs 였다. $CuAlSe_2$/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 1.1851 eV-($8.99\times10^{-4} eV/K)T^2$/(T+153k)였다. 광전류 스펙트럼으로 부터 Hamilton matrix(Hopfield quasicubic mode)법으로 계산한 결과 crystal field splitting Δcr값이 0.0087eV이며 spin-orbit Δso값은 0.2329 eV임을 확인하였다. 10K일 때 광전류 봉우리들은 n = 1일때 $A_1-, B_1$-와 $C_1$-exciton봉우리임을 알았다.

• 한국결정성장학회지
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• 제13권3호
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• pp.132-138
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• 2003

수평 전기로에서 $CdIn_2Te_4$ 다결정을 용응법으로 합성하고 Bridgman법으로 tetragonal structure의 $CdIn_2Te_4$ 단견정을 성장시켰다. c축에 수직한 시료의 광흡수와 광전류 spectra를 293k에서 10K까지 측정하였다. Hall효과는 van der Pauw 방법에 의해 측정되었으며, 온도에 의존하는 운반자 농도와 이동도는 293 K에서 각각 $8.61\times 10^{16}\textrm{cm}^3,\;242\textrm{cm}^$V .s였다. $CdIn_2Te_4$ 단결정의 광흡수와 광전류 spectra를 293k에서 10K까지 측정하였다. 광흡수 스펙트럼으로부터 band gap $E_g$(T)는 Varshni 공식에 따라 계산한 결과 $1.4750ev - (7.69\times10^{-3})\; ev/k)\;T^2$/(T + 2147k)이었다. 광전류 스펙트럼으로부터 Hamilton matrix(Hopfield quasicubic mode)법으로 계산한 결과 crystal field splitting Δcr값이 0.2704 eV이며 spin-orbit $\Delta$so값은 0.1465 eV임을 확인하였다. 10K일 때 광전류 봉우리들은 n : 1일때 $A_\;{1-} B_\;{1-}$와 $C_\;{1-}$-exciton봉우리임을 알았다

• 한국결정학회지
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• 제12권4호
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• pp.197-206
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• 2001

수평 전기로에서 AgInS₂ 다결정을 합성하여 HWE(Hot Wall Epitaxy)방법으로 AgInS₂ 단결정 박막을 반절연성 GaAs(100)기판에 성장시켰다. AgInS₂ 단결정 박막의 성장 조건은 증발원의 온도 680℃, 기판의 온도 410℃였고 성장 속도는 0.5㎛/hr였다. AgInS₂ 단결정 박막의 결정성의 조사에서 10 K에서 광발광(photoluminescence)스펙트럼이 597.8 nm(2.0741 eV)에서 exciton emission스펙트럼이 가장 강하게 나타났으며, 또한 이중결정 X-선 요동곡선(DCRC)의 박폭치(FWHM)도 121 arcsec로 가장 작아 최적 성장 조건임을 알수 있었다. Hall 효과는 van der Pauw 방법에 의해 측정되었으며, 온도에 의존하는 운반자 농도와 이동도는 293K에서 각각 9.35×10/sup 16/㎤, 294㎠/V·s 였다. AgInS₂ /SI(SEmi-Insulated) GaAs(100) 단결정 박막의 광흡수와 광전류 spectra를 293K에서 10K까지 측정하였다. 광흡수 스펙트럼으로부터 band gap E/sub g/(T)는 Varshni 공식에 따라 계산한 결과 2.1365eV-(9.89×10/sup-3/eV/K/)T²(T+2930K)이었으며 광전류 스펙트럼으로부터 Hamiltopn matrix(Hopfield quasicubic mode)법으로 계산한 결과 crystal field splitting Δcr값이 0.1541eV이며 spin-orbit Δso 값은 0.0129eV임을 확인하였다. 10K일때 광전류 봉우리들은 n=1 일때 A₁-, B-₁와 C₁-exction 봉우림을 알았다.

• 센서학회지
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• 제23권2호
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• pp.134-141
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• 2014

A stoichiometric mixture of evaporating materials for $BaIn_2Se_4$ epilayers was prepared from horizontal electric furnace. To obtain the single crystal thin films, $BaIn_2Se_4$ 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 $620^{\circ}C$ and $400^{\circ}C$, respectively. The crystalline structure of the epilayers was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of $BaIn_2Se_4$ epilayers measured from Hall effect by van der Pauw method are $8.94{\times}10^{17}cm^{-3}$ and 343 $cm^2/vs$ at 293 K, respectively. The temperature dependence of the energy band gap of the $BaIn_2Se_4$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)$=2.6261 eV-$(4.9825{\times}10^{-3}eV/K)T^2/(T+558 K)$. The crystal field and the spin-orbit splitting energies for the valence band of the $BaIn_2Se_4$ have been estimated to be 116 meV and 175.9 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 $BaIn_2Se_4/GaAs$ epilayer. The three photocurrent peaks observed at 10 K are ascribed to the $A_1-$, $B_1$-exciton for n = 1 and $C_{21}$-exciton peaks for n=21.

• 한국결정성장학회지
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• 제25권5호
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• pp.173-181
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• 2015

A stoichiometric mixture of evaporating materials for $BaIn_2S_4$ single crystal thin films was prepared from horizontal electric furnace. To obtain the single crystal thin films, $BaIn_2S_4$ 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 $620^{\circ}C$ and $420^{\circ}C$, respectively. The crystalline structure of the single crystal thin films was investigated by double crystal X-ray diffraction (DCXD). The carrier density and mobility of $BaIn_2S_4$ single crystal thin films measured from Hall effect by van der Pauw method are $6.13{\times}10^{17}cm^{-3}$ and $222cm^2/v{\cdot}s$ at 293 K, respectively. The temperature dependence of the energy band gap of the $BaIn_2S_4$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)=3.0581eV-(3.9511{\times}10^{-3}eV/K)T^2/(T+536K)$. The crystal field and the spin-orbit splitting energies for the valence band of the $BaIn_2S_4$ 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 $BaIn_2S_4/GaAs$ epilayer. The three photocurrent peaks observed at 10 K are ascribed to the $A_1$-, $B_1$-exciton for n = 1 and $C_{24}$-exciton peaks for n = 24.

• 한국전기전자재료학회논문지
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• 제24권1호
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• pp.1-6
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• 2011

Optical gain characteristics of $1.3{\mu}m$ type-II GaAsSb/InGaNAs/GaAs trilayer quantum well structures were studied using multi-band effective mass theory. The results were compared with those of $1.3{\mu}m$ GaAsSb/InGaNAs/GaAs trilayer quantum well structures. In the case of $1.3{\mu}m$ GaAsSb/InGaNAs/GaAs trilayer quantum well structure, the energy difference between the first two subbands in the valence band is smaller than that of $1.3{\mu}m$ GaAsSb/InGaNAs/GaAs trilayer quantum well structure. Also, $1.3{\mu}m$ GaAsSb/InGaNAs/GaAs trilayer quantum well structure shows larger optical gain than $1.3{\mu}m$ GaAsSb/InGaNAs/GaAs trilayer quantum well structure. This means that GaAsSb/InGaNAs/GaAs system is promising as long-wavelength optoelectronic devices for optical communication.