Effect of current flow direction on the heteroepitaxial growth of InSb films on Ge/Si(001) substrate heated by direct current

Germanium is a suitable material as the buffer layer for the heteroepitaxial growth of InSb films on a Si(001) substrate. It reduces the large lattice mismatch of about 19.3% between Si and InSb to about 14.5%. InSb films grown on the islanded Ge buffer layers on a Si(001) substrate at elevated temperature are strongly oriented in (001) direction. The bias for heating the substrate was changed in both directions; usual and reverse. Two-step growth procedure is effective to improve the crystal quality and the surface morphology of the InSb films. However, the surface morphology of the films was divided into two regions; the first region is smooth, whereas the second region consists of the colligated crystals. The smooth surface appears near the positive electrode in the usual bias condition. On the contrary, in the reverse bias condition, the smooth surface appears near the reverse electrode. The similar results were obtained for the growth of InSb on Ge(001) substrate. These results may not be due to the thermal gradient of the substrate. (C) 2000 Elsevier Science B.V. All rights reserved. PACS: 81.05.Ea: 81.10.Hi; 66.30.Q.