Abstract
Undoped semi-insulating (SI) InP wafers were obtained by high-temperature annealing under high phosphorus over pressure. These wafers show resistivities higher than 10(7) OMEGA cm, with mobilities greater than 4000 cm2 V-1 s-1. The SI properties could be held even after cap annealing with SiNx films at 700-degrees-C for 15 min. The activation energy of deep levels causing the semi-insulation was estimated as 0.64 eV. Photoluminescence measurements made on undoped SI InP show hitherto unknown peaks in the long wavelength region between 1000 and 1400 nm.