Ab initio study of defects in compound semiconductors = 화합물 반도체의 결함에 대한 제일원리 연구

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We investigate the stability of carbon acceptors and defect complexes composed of carbon and hydrogen in GaAs through first-principles pseudopotential calculations. A carbon-hydrogen $C^{-}_As-(HC_As)^0$ complex with two $C_As$ atoms at second neighbor As sites is found to be energetically more favorable than the isolated configuration of $C^{-}_As$ and $H-C_As$. We also find that a $(H-C_As)_2$ complex containing two H atoms is more stable than two isolated $H-C_As$ pairs. Hydrogen dissociation from the $C_As^{-}-(HC_As)^0$ center upon annealing leads to the formation of a $C_As-C_As$ pair, and the $C_As-C_As$ complex subsequently dissociates into two isolated $C_As$ acceptors. Here we propose a dissociation process that involves a C-C split interstitial complex at an As site and a second neighbor As vacancy, with an energy barrier of about 1.7 eV which is similar to that for Zn diffusion. We investigate the atomic geometry and energetics of Cl-related defects in ZnTe through first-principles pseudopotential calculations. We find a new type of defect which results from large lattice relaxations, with $C_3v$ symmetry and triple broken bonds around the Cl impurity at a Zn sublattice site. The triple-broken-bond structure of $Cl_Zn$ behaves as an acceptor and this defect is more stable than the DX-like broken-bond state of $Cl_Te$. Thus, we suggest that the triple-broken-bond centers are very effective in donor compensation, particularly, in heavily Cl-doped ZnTe as well as in samples grown under Te-rich conditions. We calculate the defect formation energies and concentrations of native and Mg-related defects in wurtzite and zincblende GaN using a first-principles pseudopotential method. For both the wurtzite and zincblende structures, vacancies are found to be more stable than other intrinsic defects, such as interstitials and antisites. Under Ga-rich condition, the concentration of $V^+_N$ is estimated to be about $10^17cm^{-3}$ in the absence of other impuriti...
Advisors
Chang, Kee-Jooresearcher장기주researcher
Description
한국과학기술원 : 물리학과,
Publisher
한국과학기술원
Issue Date
1998
Identifier
135078/325007 / 000945292
Language
eng
Description

학위논문(박사) - 한국과학기술원 : 물리학과, 1998.2, [ viii, 77 p. ]

Keywords

제일원리; 쑤도포텐셜; First-principles; Defect; 화합물 반도체; 결함; Pseudopotential; Compound semiconductor

URI
http://hdl.handle.net/10203/47844
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=135078&flag=dissertation
Appears in Collection
PH-Theses_Ph.D.(박사논문)
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