Epitaxial germanium–silicon structures obtained in ultrahigh vacuum

The main regularities of formation of epitaxial germanium-silicon structures at condensation in the pure UHV by the method of molecular beams and ion sputtering are considered. The influence of the preparation conditions of the substrate surface and of the condensation on the film structure and film-structure interfaces is studied. The role of carbide particles and pseudomorphism in the formation of the film structure and surface morphology is shown. The conditions for obtaining an atomically clean silicon surface without carbide particles are determined. Data on electrophysical properties of films and junctions, in particular, p-n junctions, which are formed on the silicon surface, are given. The germanium films of both p- and n-type are obtained. The concentration of current carriers ranges from 1016 to 1018 cm−3 and the mobility from 600 to 1000 cm2/Vs (293 K) and from 2000 to 6000 cm2/Vs (77 K). The structures show a maximum of spectral photosensitivity in the region of 0.9 to 1 μm.