Cleaning chemistry of InSb(100) molecular beam epitaxy substrates

Publisher Website
Google Scholar
Abstract
In order to obtain good epitaxial growth, in situ cleaning procedures are necessary. The procedures in use include argon ion bombardment and growth of an oxide passivation layer which is removed in situ by heat treatment. Several chemical cleaning procedures for InSb(100) have been compared, and a new technique based on growth of a chloride—rather than an oxide—over-layer is proposed. The chloride is found to be easily removed at low temperatures (<350 °C), and carbon contamination is minimized. Procedures for growth of the chloride are described, including growth of an oxide followed by nucleophilic substitution by Cl− ions, and direct attack on the substrate by a Cl2 plasma or Cl radicals in solution. In all cases, the film is composed of indium chlorides. In-situ desorption of the chloride formed by the Cl2 plasma is found to give the most reproducibly clean surfaces, as determined by x-ray photoemission spectroscopy.