Mutual passivation effects in highly mismatched group III-V-N alloys

The authors have recently discovered a new effect in the dilute InGaAsN alloy system in which electrically active substitutional Si donors and isoelectronic N atoms passivate each other's activity. This is manifested in a drastic reduction of the free electron concentration and, simultaneously, an increase in the fundamental bandgap in Si-doped InGaAsN alloys. Systematic studies of the mutual passivation effect in Si-doped InGaAsN alloys show that the passivation process is controlled by the diffusion of Si to the nearest neighbours of N-occupied sites, forming nearest neighbour Si-N pairs. Analytical calculations of the passivation process based on Ga-vacancy-mediated diffusion show good agreement with the experimental results. It is shown that the mutual passivation provides a method to precisely control electrical properties of InGaAsN:Si. Investigations were made of scattering mechanisms limiting electron mobility in InGaAsN through a judicious choice of the annealing conditions to vary the electron concentration by more than two orders of magnitude. The mobility of free electrons in InGaAsN is quantitatively explained on the basis of the band anticrossing model.