A INTRODUCTION

Ion implantation is widely used as a means of doping layers in silicon integrated circuit technology. However, the technique is not so easily applied to compound semiconductors which decompose during subsequent heat treatment. The process of ion implantation introduces damage to the lattice which for high doses of heavy ion species results in a highly disordered material which in the extreme can become amorphous. This damage can be removed by a post implantation heat treatment in which the damaged layer regrows by solid phase epitaxy onto the underlying single crystal substrate. The process is well controlled and reproducible for implants in silicon, but for compound semiconductors, annealing is difficult and often not reproducible. The problem is how to protect the surface from decomposing during the necessary annealing cycle. The most usual method employed for GaAs is to encapsulate the implanted surface with a thin layer of silicon nitride, which if done correctly allows samples to be processed to temperatures of around 1000 C without significant decomposition. Annealing temperatures employed by industry for processing GaAs devices and circuits tend to be rather less than this. There has been less interest in the doping of InP by ion implantation than in the doping of GaAs and, as a consequence, the problems of implanting and annealing InP are less well developed and understood. There are however many publications on the topic and it is the aim of this Datareview to summarise the data...