Ab initio calculations on the compensation mechanisms in InP

Compensation mechanisms which become semi-insulating InP from intrinsic n-type materials are investigated by first principles total energy calculations. Associated to the possible mechanisms two intrinsic defects are shown to play an important role in the transition, induced by annealing, from the n-type to the semi-insulating character. The single defect VIn3− results from the In-vacancy–H-complex, which, before the annealing, was identified by infra-red spectra as responsible for the n-type conductivity, and the PIn+VP complex defect comes from the diffusion of the neutral In vacancy. Both defects are shown to present localized levels inside the band gap which compensate for the free electron.