Introduction

The tendency for the vacancy to act as a trap for hydrogen has been well studied in many semiconductors over recent years. The structure and vibrational properties of vacancy-hydrogen complexes in silicon have been systematically investigated both theoretically[#!goss!#,#!estreich!#,#!xu!#] and experimentally[#!goss!#,#!xie!#,#!bech!#] resulting in reliable assignments of many of the local vibrational modes. We discuss the results of infrared experiments on ion-implanted Ge and ab initio modelling. A full report on techniques used will be published at a later date.