IN-SITU INVESTIGATION OF ALUMINUM GALLIUM ARSENIDE GALLIUM ARSENIDE MULTILAYER STRUCTURES UNDER INERT AND REACTIVE MEDIA BY ATOMIC-FORCE MICROSCOPY/

In this paper we describe the analytical benefits of in situ preparati on and imaging under inert and reactive media using an AlGaAs/GaAs sup erlattice structure as a well-defined model sample. Imaging under iner t organic liquids like toluene has been made possible by means of a ho me-built sample holder which has been designed for mechanical mounting of small-scale, cleaved specimens and which works without polymer sea ls in the liquid cell. The results show that sensitive surfaces can be protected from atmospheric influences without the need for ultrahigh- vacuum conditions. Contrast development on the AlGaAs/GaAs system by p referential oxidation on the AlGaAs layers could be completely suppres sed by covering the cross-sectional cleavage surface with toluene. In situ studies of corrosion processes on oxidized AlGaAs/GaAs cleavage s urfaces have shown that 0.01 and 0.001 M HCl lead to pitting, while 0. 1 M HCl results in a clear contrast inversion of the original corrugat ion of 0.3-0.6 mm. The described in situ imaging capability significan tly enhances the information content of atomic force microscopy (AFM) images, since it allows assignment of chemical information to topograp hical features primarily seen in AFM images.