The positron states in the ternary alloys Ga1-xInxN in the zincblende struc
ture 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 diso
rder, 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 electro
n-positron momentum densities along different crystallographic directions b
ecome less flat in going from GaN to InN through the equimolar alloy Ga0.50
In0.50N. Moreover, a nonlinear dependence of the positron bulk lifetime was
found as the In concentration is increased. These results reflect the chan
ge of positron annihilation characteristics with the composition in III-V n
itride semiconductor alloys.