Hydrogen-terminated silicon substrates for low-temperature molecular beam epitaxy

Abstract

The preparation of hydrogen-terminated silicon surfaces for use as starting substrates for low-temperature epitaxial growth by molecular beam epitaxy is examined in detail. The procedure involves the ex-situ removal under nitrogen of residual oxide from a silicon substrate using a spin-clean with HF in ethanol, followed by the in-situ low-temperature desorption (150°C) of physisorbed etch residues. The critical steps and the chemical basis for these steps are examined using X-ray photoelectron spectroscopy. Impurity residues at the epilayer-substrate interface following subsequent homoepitaxial growth are studied using Auger spectroscopy, secondary ion mass spectrometry, and transmission electron microscopy. Finally, scanning tunneling microscopy is used to examine the effect of cleaning methods on substrate morphology. © 1989.