Study of the defect evolution with Fe content in semi-insulating InP by photoinduced current transient spectroscopy

Semi-insulating (SI) InP substrate is the key element for both high speed microelectronic devices and for optoelectronic integrated circuits (OEICs). Up to now, crystals have been doped with a transition element, which acts as a deep acceptor. Iron has in particular been used to generate deep level in the forbidden gap of InP, which is very effective in decreasing the free carrier concentration. Today, Fe doping during liquid encapsulation Czochralski (LEC) growth is the only reliable technique for the fabrication of InP crystals with high resistivity. The defect characterization of these substrate is of great importance to have successful devices. The Photo Induced Current Transient Spectroscopy (PICTS), first reported by Hurtes et al., is a useful technique for the characterization of deep levels in high resistivity semiconductors. It is based on the analysis of the thermal behaviour of the photocurrent transient induced by periodic light pulses. In this study, we investigate the evolution of the defects in LEC InP with the concentration of Fe introduced in the melt