Electronic structure and optical properties of low demensional systems = 저차원 구조의 전자구조 및 광학적 성질에 관한 연구

I investigate electronic structure and optical properties in the low dimensional quantum systems. ZnSSe-ZnMgSSe and GaN-AlGaN quantum well systems are studied through a variational technique based on the momentum space formalism. For the electronic states of confined carriers, an effective-mass theory is used, especially, the hole kinetic energy is described by Luttinger-Kohn (LK) Hamiltonian for ZnSSe-ZnMgSSe quantum wells and by Rashiba-Sheka-Pikus (RSP) Hamiltonian for GaN-AlGaN quantum wells. InAs-GaAs quantum dots are treated in real space using a basis expansion method for the carrier envelope functions. For the band gap tailoring, external electric fields, modulation doped barriers, and separated extra barriers are reviewed in the quantum well structures, where the exciton peaks which result from band-to-band transitions are located in the red-shift or the blue-shift region and several forbidden transitions appear due to the valence band mixing. For $ZnS_xSe_{1-x}$-based quantum wells, the exciton binding energy has the maximum value at the well width $L_w = 20 \AA$ for the sulfur content of x = 0, while the peak position is shifted to $L_w = 25$ and 30 \AA for the S contents of x = 0.05 and 0.10, respectively. In all cases, the binding energies approach the bulk value around $L_w = 300 \AA$. For the well width 80 \AA, the heavy-hole binding energies are estimated to be 26.5, 27.6, and 29.5 meV for x = 0, 0.05, and 0.1, respectively, whereas the corresponding values for the light-hole are 25.1, 27.1, and 28.0 meV. For the binary well, since our calculated peak value is much higher than previous calculations, the two-dimensional effect on the exciton binding is more significant. I also find three distinguished exciton peaks in absorption spectra, which are associated with the n = 1 and 2 heavy-holes (HH1 and HH2) and n = 1 light-hole (LH1), in good agreement with experiments. As x increases, the HH1 exciton peak increases more rapidly than the LH1 peak, a...
Advisors
Chang, Kee-Jooresearcher장기주researcher
Publisher
한국과학기술원
Issue Date
1998
Identifier
135079/325007 / 000945401
Language
eng
Description

학위논문(박사) - 한국과학기술원 : 물리학과, 1998.2, [ ix, 68 p. ]

Keywords

양자점; ZnSSe-ZnMgSSe; GaN-AlGaN; InAs-GaAs; 스트레인; 엑시톤; 흡습계수; 양자우물; Absorption coefficient; Exciton; Strain; InAs-GaAs; GaN-AlGaN; ZnSSe-ZnMgSSe; Quantum well; Quantum dot

URI
http://hdl.handle.net/10203/47845
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=135079&flag=t
Appears in Collection
PH-Theses_Ph.D.(박사논문)
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