We report the molecular beam epitaxial growth of InSb on Si(111) substrates over the temperature range 190-400 °C. Epitaxial growth is achieved by suitably adjusting the growth rate, In/Sb flux ratio and substrate temperature. For growth temperatures up to 300 °C surface morphology and epitaxial quality of the film improve with temperature, whereas above 300 °C, increase in growth temperature causes deterioration in the epitaxial quality of the film. Hall measurements revealed that the electron mobility of the film increases with growth temperature and for the film grown at 300 °C it is about 2200 cm2 V-1 s-1 at room temperature (RT). Significant improvement in the electrical properties of the film is achieved using a two-step growth procedure, which involves a 300 Å thick interface layer growth at 300 °C followed by growth at 400 °C. Electron mobility of a 1.8 µm thick two-step grown film at RT is 23 000 cm2 V-1 s-1 (≈19 000 cm2 V-1 s-1 at 70 K). This is the highest mobility value we came across for an InSb film grown on a Si(111) substrate without buffer layer. Surface morphology, crystal quality and electrical properties of the grown films are discussed with respect to growth parameters.
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