• 한국결정성장학회지
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• 제17권5호
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• pp.179-186
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• 2007

[ $CdGa_2Se_4$ ] 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.

• 한국재료학회지
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• 제3권6호
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• pp.645-651
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• 1993

Bulk반절연 기판 웨이퍼에 이온 주입법에 의한 기존의 GaAs집적회로 제작시 발생하는 문제점을 보완하고자 반절연 기판 위에 반절연성의 고저항 GaAs 에피층을 성장하는 연구를 수행하였다. 먼저 반절연 기판의 EPD분포를 조사하고, MOCVD와 MBE법을 이용하여 undeped GaAs반절연성 에피층을 성장시켜 실제 집적회로의 제작에 적합한지를 평가하였다. 평가방법은 반절연성 에피\ulcorner을 buffer층으로 성장시킨 에피 기판에 ungated FET를 제작하여, 이 반절연성 에피\ulcorner을 통한 누설전류를 측정하고, 또한 반절연 기판의 EP분호의 영향을 조사하였다. 누설 전류의 측정결과 비교적 주설 전류가 큰 1$\mu\textrm{m}$ 두께의 MOCVD시료에서도 270nA/mm로 FET의 pinch-off에는 영향을 주지 못하는 매우 작은 누설 전류 값을 나타내었다. 또한 누설전류의 분포가 반절연 기판의 EPD분포와 일치하는 것을 발견하여, 에피층의 quality에 기판의 결함이 미치는 영향을 확인하였다. MBE법으로 성장한 2$\mu\textrm{m}$ 두께의 undoped burrer층 시료는 휠씬 좋은 특성을 나타내었으며, 매우 균일하고 낮은 누설전류(40nA/mm)가 측정되었다.

• 한국결정성장학회지
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• 제4권1호
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• pp.11-20
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• 1994

분자선에피택시(molecular beam epitaxy)법을 이용하여 GaAs 및 ALGaAs layer를 undoped 반절연(100) GaAs 기판위에 성장하였고, 최적의 성장온도와 성장된 시료에 대한 전기적 및 광학적 특성을 조사 하였다. Undoped GaAs층의 성장에 있어서는 측정결과로 부터 As/Ga의유속비가 약 20, 성장온도가 $570^{\circ}C$일때 12K에서의 Photoluminescence 반폭치(FWHM)가 1.14meV인 결정성이 좋은 시료가 얻어졌으며, p형으로서 carrier 농도가 $1.5{\times}10^{14}cm^{-3}$ 미만이고, Hall 이동도가 300K에서 $579cm^2/V-s$인 양질의 에피층이 얻어졌다. 또한 이들 시료에서는 ODLTS, DLTS측정으로 부터 2개의 hole형 깊은 주위만이 관측되었다. Undoped AlGaAs층의 성장에 있어서는 As/(Ga+Al)의 유속비가 20이고 $60^{\circ}C$의 성장온도에서 표면 morphology와 결정성이 좋은 시료를 성장할 수 있었으며, 0.17~0.85eV에서 8개의 깊은 준위가 관측되엇다. Si이 도핑된 AlGaAs 층의 경우, PL 스펙트럼으로 부터 Si의 도핑효과를 관측할 수 있었으며, Hall 측정으로부터 300K에서 $1.5{\times}10^{16}cm^{-3}$일 때 Hall 이동도가 $2547cm^2/V-s$인 시료를 얻을 수 있었다.

• Journal of Electrical Engineering and information Science
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• 제3권2호
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• pp.239-244
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• 1998

Piezoelectric pressure sensors and pyroelectric infrared detectors based on ZnO thin film have been integrated with GaAs metal-semiconductor field effect transistor (MESFET) amplifiers. Surface micromachining techniques have been applied in a GaAs MESFET process to form both microsensors and electronic circuits. The on-chip integration of microsensors such as pressure sensors and infrared detectors with GaAs integrated circuits is attractive because of the higher operating temperature up to 200 oC for GaAs devices compared to 125 oC for silicon devices and radiation hardness for infrared imaging applications. The microsensors incorporate a 1${\mu}$m-thick sputtered ZnO capacitor supported by a 2${\mu}$m-thick aluminum membrane formed on a semi-insulating GaAs substrate. The piezoelectric pressure sensor of an area 80${\times}$80 ${\mu}$m2 designed for use as a miniature microphone exhibits 2.99${\mu}$V/${\mu}$ bar sensitivity at 400Hz. The voltage responsivity and the detectivity of a single infrared detector of an area 80${\times}$80 $\mu\textrm{m}$2 is 700 V/W and 6${\times}$108cm$.$ Hz/W at 10Hz respectively, and the time constant of the sensor with the amplifying circuit is 53 ms. Circuits using 4${\mu}$m-gate GaAs MESFETs are fabricated in planar, direct ion-implanted process. The measured transconductance of a 4${\mu}$m-gate GaAs MESFET is 25.6 mS/mm and 12.4 mS/mm at 27 oC and 200oC, respectively. A differential amplifier whose voltage gain in 33.7 dB using 4${\mu}$m gate GaAs MESFETs is fabricated for high selectivity to the physical variable being sensed.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
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• pp.79-80
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• 2006

A stoichiometric mixture of evaporating materials for $CdIn_2S_4$ single crystal thin films was prepared from horizontal electric furnace. To obtain the single crystal thin films, $CdIn_2S_4$ mixed crystal was deposited on thoroughly etched semi-Insulating GaAs(100) substrate by the Hot Wall Epitaxy (HWE) system. The temperature dependence of the energy band gap of the $CdIn_2S_4$ obtained from the absorption spectra was well described by the Varshni's relation. $E_g(T)=2.7116 eV-(7.74{\times}10^{-4} eV)T^2/(T+434)$. The crystal field and the spin-orbit splitting energies for the valence band of the $CdIn_2S_4$ have been estimated to be 0.1291 eV and 0.0248 eV, 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 $AgInS_2$/GaAs epilayer. The three photocurrent peaks observed at 10K are ascribed to the $A_1-$, $B_1-$, and C1-exciton peaks for n = 1.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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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.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.141-142
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• 2008

Single crystal $ZnIn_2S_4$ layers were grown on thoroughly etched semi-insulating GaAs(100) substrate at $450^{\circ}C$ with hot wall epitaxy (HWE) system by evaporating $ZnIn_2S_4$ source at $610^{\circ}C$. The temperature dependence of the energy band gap of the $ZnIn_2S_4$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g$(T) = 2.9514eV - ($7.24\times10^{-4}$ eV/K)$T^2$/(T + 489 K). After the as-grown $ZnIn_2S_4$ single crystal thin films was annealed in Zn-, S-, and In-atmospheres, the origin of point defects of $ZnIn_2S_4$ single crystal thin films has been investigated by the photoluminescence(PL) at 10 K. The native defects of $V_{Zn}$, $V_s$, $Zn_{int}$, and $S_{int}$, obtained by PL measurements were classified as a donors or acceptors type. And we concluded that the heat-treatment in the S-atmosphere converted $ZnIn_2S_4$ single crystal thin films to an optical p-type. Also, we confirmed that In in $ZnIn_2S_4$/GaAs did not form the native defects because In in $ZnIn_2S_4$ single crystal thin films existed in the form of stable bonds.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
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• pp.386-391
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• 2003

Sing1e crystal $CuAlSe_2$ layers were grown on thoroughly etched semi-insulating GaAs(100) substrate at $410^{\circ}C$ with hot wall epitaxy (HWE) system by evaporating $CuAlSe_2$source at $680^{\circ}C$. 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 $CuAlSe_2$ thin films measured with Hall effect by van der Pauw method are $9.24{\times}10^{16}\;cm^{-3}$ and $295\;cm^2/V{\cdot}\;s$ at 293 K, respectively. The temperature dependence of the energy band gap of the $CuAlSe_2$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)\;=\;2.8382\;eV\;-\;(8.86\;{\times}\;10^{-4}\;eV/K)T^2/(T\;+\;155K)$. After the as-grown single crystal $CuAlSe_2$ thin films were annealed in Cu-, Se-, and Al-atmospheres, the origin of point defects of single crystal $CuAlSe_2$ thin films has been investigated by PL at 10 K. The native defects of $V_{Cd}$, $V_{Se}$, $Cd_{int}$, and $Se_{int}$ obtained by PL measurements were classified as donors or accepters. And we concluded that the heat-treatment in the Cu-atmosphere converted single crystal $CuAlSe_2$ thin films to an optical n-type. Also, we confirmed that Al in $CuAlSe_2/GaAs$ did not form the native defects because Al in single crystal $CuAlSe_2$ thin films existed in the form of stable bonds.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
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• pp.282-285
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• 2003

Single crystal $CuAlSe_2$ layers were grown on thoroughly etched semi-insulating GaAs(100) substrate at $410\;^{\circ}C$ with hot wall epitaxy (HWE) system by evaporating $CuAlSe_2$ source at $680\;^{\circ}C$. 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 $CuAlSe_2$ thin films measured with Hall effect by van der Pauw method are $9.24{\times}10^{16}\;cm^{-3}\;and\;295\;cm^2/V{\cdot}s$ at 293 K, respectively. The temperature dependence of the energy band gap of the $CuAlSe_2$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)\;=\;2.8382\;eV\;-\;(8.68\;{\times}\;10^{-4}eV/K)T^2/(T\;+\;155\;K)$. The crystal field and the spin-orbit splitting energies for the valence band of the $CuAlSe_2$ have been estimated to be 0.2026 eV and 0.2165 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 ${\Gamma}_5$ states of the valence band of the $CuAlSe_2$. The three photocurrent peaks observed at 10 K are ascribed to the $A_1-$, $B_1-$, and $C_1$-exciton peaks for n = 1.

• 한국전기전자재료학회논문지
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• 제16권10호
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• pp.871-880
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• 2003

Single crystal CuAlSe$_2$ layers were grown on thoroughly etched semi-insulating GaAs(100) substrate at 410 C with hot wall epitaxy (HWE) system by evaporating CuAlSe$_2$ source at 680 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 CuAlSe$_2$ thin films measured with Hall effect by van der Pauw method are 9.24${\times}$10$\^$16/ cm$\^$-3/ and 295 cm$^2$/V $.$ s at 293 K, respectively. The temperature dependence of the energy band gap of the CuAlSe$_2$ obtained from the absorption spectra was well described by the Varshni's relation, Eg(T) = 2.8382 eV - (8.86 ${\times}$ 10$\^$-4/ eV/K)T$^2$/(T + 155K). After the as-grown single crystal CuAlSe$_2$ thin films were annealed in Cu-, Se-, and Al-atmospheres, the origin of point defects of single crystal CuAlSe$_2$ thin films has been investigated by PL at 10 K. The native defects of V$\_$cd/, V$\_$se/, Cd$\_$int/, and Se$\_$int/ obtained by PL measurements were classified as donors or acceptors. And we concluded that the heat-treatment in the Cu-atmosphere converted single crystal CuAlSe$_2$ thin films to an optical n-type. Also, we confirmed that Al in CuAlSe$_2$/GaAs did not form the native defects because Al in single crystal CuAlSe$_2$ thin films existed in the form of stable bonds.