SCANNING ELECTRON-MICROSCOPIC DETERMINATI ON OF LAYER THICKNESS IN NANOMETRIC HETEROSTRUCTURES OF NANOMETRIC GAAS-ALXGA1-XAS

Nanometric layers on GaAs-Al(x)Ga1-xAs heterostructures, was observed using scanning electron microscopy (SEM). Multi-layer heterostructures of GaAs-Al(x)Ga1-xAs deposited on GaAs substrate were grown by liquid phase epitaxy with different Al contents, and thicknesses of each lay er. Since the measurement of the thickness layers is not possible by o ptical microscopy, the samples have to be specially prepared to be ana lyzed by SEM. The method consists in observing a selectively etched fr esh cleaved facet. After etching a new cleaved surface is made on the perpendicular direction of the first one. The layer thickness is then obtained by measuring the step relief on this new surface produced by the etching solution and the cleavage. As a result thicknesses as thin as 50 nm have been measured.