INSITU ANALYSIS OF GALLIUM-ARSENIDE SURFACES BY COAXIAL IMPACT COLLISION ION-SCATTERING SPECTROSCOPY WITH AN OFF-AXIS ION-SOURCE

A novel coaxial impact collision ion-scattering spectroscopy system with an off-axis ion source has been designed and constructed. By inserting a deflecting electrode in the primary ion-beam line, the ion source was arranged on the off-axis position of the line connecting the target and the detector. This configuration has resulted in high-resolution mass analysis and a high counting rate. This system has been applied to an in situ analysis of molecular beam epitaxial surfaces. It was found that signals scattered by Ga atoms and those by As atoms could be separately detected within the sensitivity of one monolayer GaAs on an AlAs layer and within a sampling depth of 2∼3 monolayers. © 1990 IOP Publishing Ltd.