MEASUREMENT OF INTERFACE ROUGHNESS IN A SUPERLATTICE OF DELTA-BARRIERS OF AL IN GAAS USING HIGH-RESOLUTION X-RAY-DIFFRACTOMETRY

Aluminium delta-barriers grown in GaAs at 400 degrees C by molecular b eam epitaxy have been studied using high-resolution x-ray diffractomet ry. Superlattice structures of up to 100 periods enabled measurement o f layers containing fractions of a monolayer of Al. It was also possib le to determine the period variation and interface roughness or gradin g to a depth resolution of about a monolayer by measuring the weak, hi gh-order satellites around the 002 Bragg reflection. Dynamical simulat ions showed that there was no interface roughness or grading beyond tw o monolayers depth. The results were compared with those from Si delta -doped GaAs, in order to provide an understanding of Si delta-doping, which has a wide range of device applications.