서지주요정보
도핑이 많이 된 n형 GaAs와 InGaP의 광학적 특성에 관한 연구 = Study on optical properties of heavily n-doped GaAs and InGaP
서명 / 저자 도핑이 많이 된 n형 GaAs와 InGaP의 광학적 특성에 관한 연구 = Study on optical properties of heavily n-doped GaAs and InGaP / 이남영.
저자명 이남영 ; Lee, Nam-Young
발행사항 [대전 : 한국과학기술원, 1996].
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소장정보

등록번호

8006866

소장위치/청구기호

학술문화관(문화관) 보존서고

DPH 96027

SMS전송

도서상태

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초록정보

In this thesis, the heavy doping effects in heavily Si-doped GaAs and DX center characteristics in n-doped $In_{0.32}Ga_{0.68}P$ were investigated by using optical measurements such as photoluminescence (PL) or photoreflectance (PR) spectroscopy. Si-doped GaAs samples were grown by molecular beam epitaxy. The electron concentration n of the samples ranged from $1.0×10^{17}$ to $4.2×10^{18} cm^{-3}$. A line-shape analysis of room temperature PL spectra was carried out. It was found that the conduction band tail $η_c$ and the Fermi energy $ε_f$ measured from the conduction band minimum could be expressed as $η_c=2.0× 10^{-8}n^{1/3}$ (eV) and $ε_f=-0.074+1.03×10^{-7} n^{1/3}$ (eV), respectively. The PL peak energy, at which the electron concentration per unit energy in the conduction band is maximum, could also be expressed as $1.426+2.4×10^{-14} n^{2/3}$ (eV). From the empirical $n^{1/3}$ power dependence of $η_c$, we suggest that the band-gap narrowing, induced by band tail formation in heavily n-doped GaAs, should also show the $n^{1/3}$ power dependence. PL spectra of heavily Si-doped GaAs were investigated at 20 K as a function of electron concentration. We found that the two maxima in the electron populations of the conduction band and the donor band, respectively, merged as the doping concentration increased, and could not be distinguished at the electron concentration of the order of $10^{18} cm^{-3}$. We also studied the temperature-dependent behavior of 1.49 eV PL peak known to be due to the donor-acceptor (DA) pair recombination in heavily Si-doped GaAs. In some cases, the 1.49 eV PL peak was observed to appear up to much higher temperature than a normal DA peak is. The temperature dependence of this peak energy was very similiar to that of the band-gap energy. From this fact, it is discussed that this abnormal PL peak must be the artifact due to the remaining region of the PL spectrum reflected from the back surface after being absorbed in epilayers and substrate, while it travels back and forth. It was found that, for highly degenerate semiconductors, the critical energy measured by the PR equals to the peak energy of the PL spectrum. When Fermi level lies below the conduction-band minimum, the PR spectra reveals the band-gap energy as well as the energy $E_{max}$ at which the electron concentration per unit energy in the donor band becomes maximum, and this maximum was observed to merge in the conduction-band at about $3×10^{17}cm^{-3}$ electron concentration. $In_{0.32}Ga_{0.68}P$ samples doped with IV elements S, Se, and Te were prepared by liquid phase epitaxy in the range of $n=10^{17}×10^{18} cm^{-3}$. The PL characteristics of the InGaP samples were studied in the temperature range of 20K~300K. At low temperture, two main peaks at about 2.26 eV and at about 2.17 eV, respectively, were consistently observed and they are attributed to the near band-edge emission and donor-to-acceptor transitions, respectively. A third peak was observed at about 2.21 eV positions for all samples as the sample temperature was increased. After the deconvolution of all measured PL spectra with the three peaks, the peak characteristics were investigated as a function of temperature. It was found that the third peak is due to the capturing of the conduction electrons by the DX center. The blue shift of the third peak energy was observed for all samples as the laser intensity was increased. From this shift, we could understand that the third peak should be generated by the recombination between an electron captured by DX center and an acceptor bound hole. It was also observed that the band gap energy showed the blue shift when the temperature was increased in the low temperature range. It was found that the temperature which showed the maximum blue shift nearly equaled to the temperature at which persistent photoconductivity disappeared. From this fact, we could know the blue shift is induced by the change of many body effect while the conduction electrons are captured by the DX centers. The ratios of DX center density to doping concentration (n_{DX}/n) could be determined from the shift of band gap energy. The values were 0.21, 0.07, and 0.08 for S-, Se-, and Te-doped $In_{0.32}Ga_{0.68}P}$ samples, respectively.

서지기타정보

서지기타정보
청구기호 {DPH 96027
형태사항 iii, 109 p. : 삽도 ; 26 cm
언어 한국어
일반주기 저자명의 영문표기 : Nam-Young Lee
지도교수의 한글표기 : 박해용
지도교수의 영문표기 : Hae-Yong Park
수록잡지명 : "Determination of conduction band tail and Fermi energy of heavily Si-doped GaAs by room-temperature photoluminescence". Journal of Applied Physics. American Institute of Physics, vol. 78, no. 5, pp. 3367-3370 (1995)
학위논문 학위논문(박사) - 한국과학기술원 : 물리학과,
서지주기 참고문헌 : p. 103-109
주제 GaAs
InGaP
Photoluminescence
Photoreflectance
Heavy doping effect
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