1,720,978 research outputs found
Nitrogen-doping efficiency in ZnSe and ZnTe
No full textWe perform first-principles pseudopotential calculations to explain the difference in nitrogen-doping levels between ZnSe and ZnTe. Calculating the formation energies for various N-related and native defects, rye estimate the hole carrier density in ZnSe to be about 10(18) cm(-3), in good agreement with experiments. In ZnTe, the formation energy of a N acceptor is found to be lower by about 0.13 eV, thus, the hole carrier density is higher by about 5 times, compared with ZnSe. At high doping levels above 10(19) cm(-3), the doping efficiency falls rapidly due to the neutralization by inert N-2 molecules or the compensation effect by split-interstitial N-N complexes, depending on stoichiometry.
STRUCTURE AND STABILITY OF THE DX-CENTERS IN GAAS AND INP
No full textWe review some of the recent theoretical studies on the atomic structure, the stability, and the vibrational modes of donor-induced defect levels in GaAs and InP. For Si and S donors, the microscopic origin of the DX center is investigated and a review is given of the shallow-to-deep DX level transition under hydrostatic pressure. We also discuss the band structure and the chemical bonding effects on the stability of donor impurities, which are associated with broken-bond and breathing-mode lattice relaxations
COMPENSATION AND DIFFUSION MECHANISMS OF CARBON DOPANTS IN GAAS
No full textWe perform first-principles theoretical studies for the doping efficiency and the diffusion mechanism of carbon dopants in GaAs. The C acceptor occupying an As site is found to be the most stable and is responsible for the high doping efficiency; however, the hole concentration is saturated to about 10(20) cm-3 due to the compensation by the donors such as the [100]-split interstitial (CC)[100] complexes. We propose a mechanism for C diffusion accompanied with the formation and dissociation of the (CC)[100] complex, with the activation energy lower than that for atomistic diffusion
THEORY OF DEFECT STABILITY AND SELF-DIFFUSION MECHANISM IN CARBON-DOPED GAAS
No full textThe defect stability and the diffusion mechanism of C in GaAs are investigated through ab initio pseudopotential calculations. The most predominant defect is found to be a C-AS acceptor. Lattice relaxations around the substitutional C(As) defect are significant. Thus, the C(As) defect is energetically quite stable, which may explain the low diffusivity of C observed in GaAs. However, as the C concentration exceeds above 10(19) cm-3, the concentration of [100]-split interstitial C-C complexes increases abruptly. This C-C complex compensates for hole carriers and affects the diffusion process of C
Atomic structure and Dynamical Properties of the Shallow and Deep Donors in GaAs and InP
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