Nitrogen isoelectronic trap in GaAs/sub 1-x/P/sub x/: II. Model calculation of the electronic states N/sub Gamma/and N/sub x/ at low temperture
A semiphenomenological theory of the isolated N isoelectronic trap in GaAs/sub 1-x/P/sub x/ is presented, based on an extended (multisite), one-band Koster-Slater model of the electron-impurity interaction, including the effects of both the central-cell atomic pseudopotential difference and the spatially extended lattice distortion surrounding the substitutional nitrogen impurity. The alloy host is treated in a virtual-crystal approximation. The parameters of the model are determined by fitting low-temperature photoluminescence data from ion-implanted materials of two compositions selected near x approx. = 0.35. The model yields both a spatially localized N/sub X/ (or A) state which evolves continuously with decreasing x from the A line of GaP, and a spatially-diffuse state N/sub Gamma/which is present in near-direct and direct-band-gap alloys (0.3 9 or approx. = x 9 or approx. = 0.5). The theory quantitatively describes the energies of these luminescence lines as a function of alloy composition x. In addition, good agreement with the data is found for the following calculated quantities: (i) the composition dependences of the N/sub Gamma/and N/sub X/ luminescence intensities, (ii) the pressure dependences of the N/sub Gamma/and N/sub X/ intensities, (iii) the composition dependence of the N/sub X/ lifetime, and (iv) the binding energy of NN/sub 1/ pairs in GaP. The model leads to a tentative interpretation of N/sub Gamma/luminescence as originating, at least in part, from excitonic molecules.
- Research Organization:
- Department of Physics and Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
- OSTI ID:
- 7289841
- Journal Information:
- Phys. Rev., B; (United States), Vol. 16:4
- Country of Publication:
- United States
- Language:
- English
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