Calculations of impurity states in semiconductors: II. GaP:O

Abstract

For part I. see abstr. A44035 of 1973. The method developed in the authors' previous paper is applied to a calculation of the ground state energy and wavefunction of the deep donor oxygen in GaP. 21*48 sampling points, 2 valence bands and 2 conduction bands are used in the expansion for the impurity wavefunction Psi . A ground state energy of 0.696 eV from the bottom of the conduction band is obtained. A plot of mod Psi (r) mod ² and also of the wavevector dependence of the probability density are presented and compared with those for other impurities in GaP. It is found that the ground state of GaP:O is dominated by contributions from the secondary conduction band minima and it is suggested that this result may explain the pressure coefficients of some deep centres in many-valley semiconductors.