An Evaluation of the Multilayer Structures of Compound Semi-conductors Using Ion Sputtering Method.

Abstract

An evaluation method for mutilayered semi-conductors by Auger depth profiling analysis is described. We have determined the depth resolution function (DRF) from the Auger depth profile of GaAs/A1GaAs specimen having an abrupt interface. Then, we have applied the DRF to the analysis of an interface of GaAs/AlGaAs specimen containing an interface of aluminum graded-layer. The resulting aluminum graded-layer thickness is about 14nm, which is in good agreement with the value estimated from the growth rate of the thin layer at preparing the specimen with molcular beam epitaxy method. The general formula of the depth resolution function was obtained from the logistic function. We have also carried out the evaluation of InP/GaInAs mutilayer structures by Auger depth profiling analysis. It is very difficult to obtain the Auger depth profile of InP specimens by argon ion sputtering because of the induced surface roughness. To reduce the roughness caused by the argon ion bombardment, a specimen cooling method (at liquid nitrogen temperature) was applied to the Auger depth profiling analysis of InP (8nm)/GaInAs (6nm) mutilayered specimen. This method provided excellent results ; the mutilayered structure of the multi-quantum wells was observed clearly over the 40 structures (over the depth of 300nm).