MULTICHAMBER ULTRAHIGH-VACUUM SCANNING TUNNELING MICROSCOPE SYSTEM FOR INVESTIGATING PROCESSED GAAS-SURFACES AND OBSERVATION OF ARGON-ION-BOMBARDED GAAS-SURFACES

A multi-chamber ultrahigh vacuum scanning tunneling microscopy (UHV-STM) system has been constructed for investigations of processed GaAs surfaces. This system comprises five UHV chambers connected by UHV tunnels. A specially designed STM unit which can be used with a 23-mm-diameter molybdenum block, is installed in an STM-chamber for surface observations. A molecular beam epitaxy (MBE) chamber for epitaxial growth of GaAs layers and a process-chamber for argon ion-bombardment are included in the five chambers. First, the surface of the MBE-grown layer on a GaAs (001) wafer was observed with STM. The sample was then transferred to the process-chamber and bombarded with argon ions. Many defects, which seemed to be caused by the ion-bombardment, were found in an STM image taken with the ion-bombarded sample.