뜨거운 곁쌓기법에 의해 성장된 MgGa2Se4 단결정 박막의 광전기적 특성

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A stoichiometric mixture of evaporating materials for MgGa2Se4 single crystal thin films was prepared from horizontal furnace. To obtain the single crystal thin films, MgGa2Se4 mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by hot wall epitaxy(HWE) system. The source and substrate temperatures were 610 ℃ and 400 ℃, 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 MgGa2Se4 single crystal thin films measured from Hall effect by Van der Pauw method are 6.21×1017 cm-3 and 248 cm2/V․sec at 293 K, respectively. From the optical absorption measurement, the temperature dependence of energy band gap on MgGa2Se4 single crystal thin films was found to be Eg(T)=2.34 eV - (8.81×10-4 eV/K)T2/(T+251 K). The crystal field and the spin-orbit splitting energies for the valence band of the MgGa2Se4 have been estimated to be 190.6 meV and 118.8 meV, respectively, by means of the photocurrent spectra and the Hopfield quasicubic model. These results indicate that the splitting of the ΔSo definitely exists in the Γ5 states of the valence band of the MgGa2Se4/GaAs epilayer. The three photocurrent peaks observed at 10 K are ascribed to the A1-, B1-, and C1-exciton peaks for n=1. After the as-grown MgGa2Se4 single crystal thin films was annealed in Mg-, Se-, and Ga-atmospheres, the origin of point defects of MgGa2Se4 single crystal thin films has been investigated by the photoluminescence(PL) at 10 K. The native defects of VMg, VSe obtained by PL measurements were classified as a donors or acceptors type. And we concluded that the heat-treatment in the Se-atmosphere converted MgGa2Se4 single crystal thin films to an optical n-type. Also, we confirmed that Ga in MgGa2Se4/GaAs did not form the native defects because Ga in MgGa2Se4 single crystal thin films existed in the form of stable bonds. In order to explore the applicability as a photoconductive cell, we measured the sensitivity(), the ratio of photocurrent to darkcurrent(pc/dc), maximum allowable power dissipation (MAPD) and response time. The results indicated that the photoconductive characteristic were the best for the samples annealed in Se vapour compare with in Mg, Ga, air and vacuum vapour. Then we obtained the sensitivity of 0.98, the value of pc/dc of 1.42×107, the MAPD of 331 mW, and the rise and decay time of 10 ms and 9.6 ms, respectively.
Alternative Title
Opto-electrical Properties for MgGa2Se4 Single Crystal Thin Film Grown by Hot Wall Epitaxy
Alternative Author(s)
Kim, Hey Jeong
조선대학교 자연과학대학 물리학과
일반대학원 물리학과
Awarded Date
Table Of Contents
Ⅰ. 서 론 ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­1

Ⅱ. 이 론 ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­ 3
A. 에너지 띠 구조 ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­3
1. 전도띠 구조와 띠간격 ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­3
a. Γ 띠와 Kane 모형 ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­3
b. L 띠와 X 띠 ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­6
2. 호울(Hole)띠의 구조 ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­7
B. 전기수송이론 ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­8
1. Boltzmann 전기수송방정식 ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­8
2. 전기수송상수 ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­10
a. Γ 띠에 대한 수송상수 ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­10
(1) 운반자 이동도 ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­11
(2) Hall 계수 ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­11
(3) Hall 산란인자 ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­11
b. 다중띠 Hall 효과와 전기전도도 ­­­­­­­­­­­­­­­­­­­­­­­­­­­12
3. 산란기구 ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­13
a. Γ 띠에서의 산란 ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­13
b. L 및 X 띠에서의 산란 ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­13
c. 호울(Hole)띠의 산란 ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­13
C. 광발광 ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­14
1. 발광성 재결합 과정 ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­ 14
2. Exciton 재결합 ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­16
a. 자유 exciton ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­16
b. Bound exciton ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­17
3. 띠간 재결합 ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­18
4. 띠와 불순물간의 재결합 ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­18
5. 주개-받개 쌍 재결합 ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­20
6. Phonon ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­22
7. 깊은 준위에 의한 전이 ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­22

Ⅲ. 실험 및 측정 ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­24
A. 다결정 합성용 수평전기로 제작 ­­­­­­­­­­­­­­­­­­­­­­­­­24
B. MgGa2Se4 다결정 합성 ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­26
C. HWE에 의한 MgGa2Se4 단결정 박막성장­­­­­­­­­­26
D. 결정구조 ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­28
E. Hall 효과 측정 ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­28
F. 광전류(Photocurrent) 측정 ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­28
G. 광발광(Photoluminescence) 측정 ­­­­­­­­­­­­­­­­­­­­­­32
H. MgGa2Se4 단결정 박막의 열처리 조건­­­­­­­­­­­­­­­ 34
I.광전도 셀 특성 ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­35

Ⅳ. 실험 결과 및 고찰 ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­36
A. MgGa2Se4의 결정구조 및 조성비 ­­­­­­­­­­­­­­­­­­­­­­­36
1. MgGa2Se4 다결정의 결정구조 ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­36
2. HWE에 의한 MgGa2Se4 단결정 박막의 성장 조건 ­­40
3. MgGa2Se4 박막의 화학 양론적 조성비­­­­­­­­­­­­­­­­­­ 43
B. MgGa2Se4 단결정 박막의 Hall 효과 ­­­­­­­­­­­­­­­­­­44
C. MgGa2Se4 단결정 박막의 광흡수 스펙트럼과 광학적 에너지 갭 ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­47
D. MgGa2Se4 단결정 박막의 광전류­­­­­­­­­­­­­­­­­­­­­­­ 52
E. MgGa2Se4 단결정 박막의 광발광 ­­­­­­­­­­­­­­­­­­­­­­­60
1. As-grown MgGa2Se4 단결정 박막의 PL 스펙트럼
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­ 60
2. Mg, Ga, Se 분위기에서 열처리한 MgGa2Se4 단결정 박막의 PL 스펙트럼 ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­63
F. 광전도 셀 특성­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­ 69
1. 감도 ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­69
2. 최대허용소비전력(MAPD) ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­71
3. pc/dc ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­73
4. 응답시간 ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­74

Ⅴ. 결 론 ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­76

References­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­ 79
조선대학교 대학원
김혜정. (2013). 뜨거운 곁쌓기법에 의해 성장된 MgGa2Se4 단결정 박막의 광전기적 특성.
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