Photoreflectance 및 Photocurrent 측정에 의한 반절연성 GaAs의 광학적 특성

김기홍,김동렬,배인호,김대년,김인수 嶺南大學校 基礎科學 硏究所 1998 基礎科學硏究 Vol.18 No.-

We report on the room temperature optical characterization of semi-insulating GaAs. The energy gap of semi-insulating GaAs was determined to be 1.41eV by photoreflectance(PR)and possible orgin of the photoreflectance signal is discussed. From photoreflectance(PC)measurement, the peak of PC is observed at 1.40 eV, corresponding to GaAs band to band transition. The influence of temperature and dependent upon the chopper frequency on the PC of semi-insulating GaAs is studied.

Al_(0.3)Ga_(0.7)As/GaAs 다중 양자우물구조에서 Photolumunescence의 온도 의존성

김동렬,배인호,김대년,박성배,신영남 大邱大學校附設 基礎科學硏究所 1998 基礎科學硏究 Vol.15 No.1

Temperature dependent photoluminescence(PL) has been applied to characterize the subband transition in Al_(0.3)Ga_(0.7)As/GaAs multiple quantum wells grown by molecular beam epitaxy. The PL signal at 295 K showed main peak located at 1.4795 eV with a shoulder around 1.4973 eV. They are associated with the E1 H1 and E1 L1. From temperature dependent PL intensity, activation energy is determined to be 22 meV. From temperature dependent PL linewidth, γ_(i) and γ_(c) are determined to be 5.26±0.2 meV, 136±52 meV, respectively. When the lattice temperature was decreased, the peak energy increased, following the temperature dependence of the bulk GaAs band gap, down to around 30 K, and then deviated to the lower energy side by about 3.5 meV at 12 K.

Chemical Beam Epitaxy로 성장한 InGaP의 Photoreflectance 특성 연구

김동렬,배인호,박성배,신영남 大邱大學校附設 基礎科學硏究所 1998 基礎科學硏究 Vol.14 No.2

In_(x)Ga(1-x)P/GaAs system were grown by chemical beam epitaxy(CBE). Pure phosphine(PH₃) gases were used as group Ⅴ sources. For the group Ⅲ sources, TEGa, TmIn were used. In_(x)Ga(1-x)P epilayer was grown on SI-GaAs substrate and has a 1- μm thick. We investigated characteristics of In_(x)Ga(1-x)P using photoreflectance(PR) spectroscopy. From PR measurement, the signal of In_(x)Ga(1-x)P shows third-derivative feature whose peaks provide energy gap. The energy gap of In_(x)Ga(1-x)P has deduced composition x. Chemical beam epitaxy(CBE)로 성장한 In_(x)Ga_(1-x)P에 대하여 photoreflectance(PR) 측정을 하였다. 측정결과, 시료의 띠 간격 에너지는 1.872 eV이었다. 이 에너지 값으로부터 In_(x)Ga_(1-x)P의 조성비 x값이 0.5임을 얻었다. 온도변화에 따른 PR 측정으로 온도계수 dE_(g)/dT=-3.773×10^(-4) eV/K 이었고, 또한 온도변화에 따른 ΔE_(8) 값으로부터 Varshni 상수 α와 β 값을 얻을 수 있었다. Bose-Einstein 온도 관계식을 이용하여 interaction의 크기 β_(B)는 19.4 meV이었고, 평균 포논 주파수와 관계되는 θ값은 101.4K 이었다.

MBE(molecular beam epitaxy)로 성장된 GaAs/AlAs 초격자의 특성연구

김동렬,김말문 嶺南大學校 基礎科學硏究所 1996 基礎科學硏究 Vol.16 No.-

GaAs/AlAs superlattice was grown by molecular beam epitaxy with a thickness of 15 monolayers. We have performed photoluminescence measurement. Measurement were performed as a function of excitation laser power and temperature. The photoluminescence peak intensity as a function of excitation laser power is well described by a straight line on logarithmic plot, indicating that radiative recombination mechanism is excitonic-like transition. Finally, we have showed the temperature dependence of the peak energy of the HI-Cl transition. When lattice temperature was decreased, the peak energy first increased, following the temperature dependence of the bulk GaAs band gap, and deviated to the lower energy side by about 4 meV at 7.2K from extrapolated curve. The observed Stokes shift is in good agreement with previous results on multiple-quantum well sample of the high quality.

(GaAs)m/(AlAs)m 단주기 초격자의 Crossover에 대한 연구

김동렬,배인호 嶺南大學校 基礎科學硏究所 1996 基礎科學硏究 Vol.16 No.-

Photoluminescence measurement is carried out to clarify the crossover from the direct to the indirect transition in ??/?? short-period superlattices(SPS) with m=15 from m=1. Energy band calculation based on the envelope function approximation shows a good agreement with the experimental observation, where ??/?? short-period superlattices are of indirect gap material for m≤12 and direct gap material for m>12.

Fe가 오염된 GaAs에서의 Photoluminescence

김동렬,유재인,배인호,박성배,신영남 大邱大學校附設 基礎科學硏究所 1998 基礎科學硏究 Vol.15 No.2

Photoluminescence(PL) has been applied to characterize the transition in contaminated n-GaAs with Iron. The PL spectrum of the bulk n-GaAs at 15 K showed two peaks, one is the DAP peak located at 1.477 eV and the other is the Ga vacancy peak around 1.4973 eV. The PL spectrum of the Fe contaminated n-GaAs showed peak located at 1.4795 eV with broade the full with half maximum that relate with Fe acceptors. From temperature dependent PL intensity, activation energy E_(u) is determined to be 35 meV.

Al0.2Ga0.8As/SI-GaAs 구조의 Photoreflectance 특성

한병국,김동렬 慶山大學校 基礎科學硏究所 1999 基礎科學 Vol.3 No.-

Al??Ga??As/GaAs 구조에 대해 photoreflectance(PR) 측정를 수행하였으며, PR 스펙트럼이 GaAs 기판으로부터 근원이되는 두 개의 신호의 중첩으로 되어 있음을 관측하였다. modulation beam power dependence으로부터, GaAs에서 PR신호를 야기시키는 photo-carrier가 계면 부근에서 발생됨이 밝혀졌다. GaAs 기판으로부터의 PR신호가 높은 변조 주파수에서 다른 기여(contribution)와 분리되어 질 수 있음을 증명했으며, 변조 주파수 의존성 측정을 통하여 이러한 것이 photo-carrier의 lifetime의 차로인한 결과로 나타남을 밝혔다. We have performed photoreflectance(PR) measurement for Al0.2Ga0.8As/GaAs structure and have observed that PR spectrum is superposition of two signals which originate from GaAs substrate. From the modulation beam power dependence, we reveal that the photo-carriers, which cause the PR signals from the GaAs, are generated at the vicinity of the interface. We have also demonstrated that PR signals from GaAs substrate can be separated from the other contributions at a high modulation frequency. Through measuring the modulation frequency dependence, we have confirmed that this results from the difference of the lifetimes of photo-carriers.

Strong Red Photoluminescence from Nano-porous Silicon Formed on Fe-Contaminated Silicon Substrate

Kim, Dong-Lyeul,Lee, Dong-Yul,Bae, In-Ho The Korean Institute of Electrical and Electronic 2004 Transactions on Electrical and Electronic Material Vol.5 No.5

The influences of the deep-level concentration of p-type Si substrates on the optical properties of nano-porous silicon (PS) are investigated by deep level transient spectroscopy (DLTS) and photoluminescence (PL). Utilizing a Si substrate with Fe contaminations significantly enhanced the PL intensity of PS. All the PS samples formed on Fe-contaminated silicon substrates had stronger PL yield than that of reference PS without any intentional Fe contamination but the emission peak is not significantly changed. For the PS 1000 sample with Fe contamination of 1,000 ppb, the maximum PL intensity showed about ten times stronger PL than that of the reference PS sample. From PL and DLTS results, the PL efficiency strongly depends on the Fe-related trap concentration in Si substrates.

맥아제조시 적색광 희사(熙射)에 의한 배유조직(胚乳組織)의 변화

김광수,김순동,김진구,신승열,김주남 한국농화학회 1987 Applied Biological Chemistry (Appl Biol Chem) Vol.30 No.1

This study was carried out to investigate the effect of the red light on embryo tissue of barley during germination. The solubility of starch in endosperm of germinated barley was different between dark and red treatments at the 3rd day of germination, but was increased by the red light from the 4th day of germination. Blue value of the starch in the germinated barley decreased rapidly from 0.42 at the 1st day to 0.13 at the 6th day in the dark, and same tendency was found in the red light, but blue value was lower in the red light than in the dark. Aleurone cell wall was swollen much faster in the red light than in the dark during germination. The cell wall was broken down more greatly in the red light than in the dark at the 5th day of germination.

아르곤 플라즈마로 처리한 n - GaAs의 표면특성에 관한 Photoreflectance 연구

이동율(Dong-Yul Lee),김인수(In-Soo Kim),김동렬(Dong-Lyeul Kim),김근형(Geun-Hyoung Kim),배인호(In-Ho Bae),김규호(Kyoo-Ho Kim),한병국(Byung-Kuk Han) 한국진공학회(ASCT) 1997 Applied Science and Convergence Technology Vol.6 No.4

Power를 40 W로 고정하고 시간을 5~120초간 변화시켜 아르콘 플라즈마로 처리시킨 n-GaAs(100)의 특성을 photoreflectance(PR) 측정으로 조사하였다. 아르곤 플라즈마 처리시간을 증가시킴에 따라 E。 피크의 세기는 처리시간이 5초일 때 최소로 관측되었으며, 이때 표면전기장(E_S), 순수 캐리어농도(N_D-N_A) 및 표면상태 밀도 (Q_(SS))는 각각 1.05×10^5 V/㎝, 1.31×10^(17) ㎝-³ 및 1.64×10^(-7) C/㎡로 이 값들은 bulk 시료에 비해 약 57.1, 81.4 및 56.9% 감소하였다. 반면에 5초일 때 compensation center 농도(N_A)는 5.57×10^(17) ㎝-³로 최대였다. 그리고 아르곤 플라즈마 처리시 유발된 결함들의 침투깊이는 표면에서 약 450 Å 정도였다. We have investigated the surface characteristics of n-GaAs (100) treated with Ar plasma (40 W, 5~120 sec) by photoreflectance (PR) measurement. With increasing Ar plasma treatment time, the intensity of E。 peak observed to the minimum at 5 sec. The surface electric field (E_S), net carrier concentration (N_D-N_A), and surface state density (Q_(SS)) are 1.05×10^5 V/㎝, 1.31×10^(17) ㎝-³ and 1.64×10^(-7) C/㎡, respectively. These values were about 57.1, 81.4 and 56.9% smaller than those of bulk n-GaAs. On the other hand, the concentration of compensation centers (N_A) was maximum with value of 5.57×10^(17) ㎝-³ at 5 sec. And penetration depth of defects generated after treated with Ar plasma was about 450 Å from surface.