The damaged layers of crystals which had been surface-treated by reactive ion etching, using PCl3 gas, were evaluated by performing capacitance-voltage, secondary ion mass spectroscopic and photocapacitance measurements. A reduction in the carrier concentration was observed at the surface, within the depth of 60 to 70nm, where Cl atoms injected at high energy were observed. Photocapacitance measurements revealed that the density of the deep levels increased with decreasing gas pressure. The deep levels were thought to be complexes of shallow donor impurities and intrinsic point defects.

Photocapacitance of Deep Levels in GaP Crystals Surface Treated by Reactive Ion Etching. H.Hashimoto, T.Saito, K.Suto, J.Nishizawa: Journal of Vacuum Science and Technology B, 2002, 20[2], 566-9