CROSS-SECTIONAL TRANSMISSION ELECTRON-MICROSCOPY OF THIN-FILM POLYCRYSTALLINE SEMICONDUCTORS BY CONVENTIONAL MICROTOMY

Conventional ultramicrotomy with a glass knife is shown to be a valuable technique for studying thin film polycrystalline semiconductor materials in cross-section. High quality sections of CuInSe2 (CIS) polycrystalline thin films and of nanocrystalline PbSe films deposited on mica, suitable for electron microscopic investigations, can be obtained in large quantities within a very short time. Detailed cross-sectional transmission electron microscopy (XTEM) studies performed on CIS films revealed columnar grains of tetragonal chalcopyrite structure that nucleate at the CIS-mica interface. The average grain diameter is about 30-60 nm and increases with increasing distance from the substrate. Intergranular voids predominantly located near the interface were commonly observed. Microtwins on (112) planes were found in many of the grains. No second phases were observed in these samples. XTEM on nanocrystalline PbSe layers on mica revealed films made up of very small spherical grains (4-5 nm in diameter) of cubic PbSe dispersed in an amorphous matrix and uniformly distributed throughout the thickness of the layer.