The EL2 center in GaAs: symmetry and metastabilityReportar como inadecuado

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Abstract : Photo-EPR, piezospectroscopic and Stark-effect photocapacitance data were used to determine the symmetry of the EL2 center in GaAs and to identify the mechanism that underlies its metastable behavior. The results unambiguously point to C3V as the type of symmetry for this antisite double donor whose charge states — D+ = AsGa, D0= AsiVGa0 and D++ = AsiVGa++ — occupying, respectively, the positions on the site and in the tetrahedral and hexagonal interstices, are brought about, in the same order, by the wavefunctions of the Γ, L and X valleys of the conduction band. The transition made by the EL2 center to a metastable state is the result of a charge exchange of the type 2D+ + hv → D0 + D++ , which causes the antisite As, defect to tunnel from its position at the site to a position in the tetrahedral interstice. Annealing of the center in this state proceeds at such temperatures and rates as are determined by the height of the energy barrier to the D0 + h → D+ reaction.

Autor: N. Bagraev



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