Composition dependence of positron states in zincblende Ga1-xInxN

The positron states in the ternary alloys Ga1-xInxN in the zincblende structure in the range from x = 0 to x = 1 have been investigated. The electron wavefunction is calculated using the pseudopotential band model within the virtual-crystal approximation. To make allowance for the compositional disorder, a correction to the alloy potential has been introduced. The positron wavefunction is evaluated under the point-core approximation for the ionic potential. The shapes of the profiles indicate that the integrated electron-positron momentum densities along different crystallographic directions become less flat in going from GaN to InN through the equimolar alloy Ga0.50In0.50N. Moreover, a nonlinear dependence of the positron bulk lifetime was found as the In concentration is increased. These results reflect the change of positron annihilation characteristics with the composition in III-V nitride semiconductor alloys.