Composition, morphology and surface recombination rate of HCl–isopropanol treated and vacuum annealed InAs(1 1 1)A surfaces

Abstract

X-ray photoelectron spectroscopy and atomic force microscopy were used to examine the chemical composition and surface morphology of InAs(1 1 1)A surface chemically etched in isopropanol–hydrochloric acid solution (HCl–iPA) and subsequently annealed in vacuum in the temperature range 200–500 °C. Etching for 2–30 min resulted in the formation of “pits” and “hillocks” on the sample surface, respectively 1–2 nm deep and high, with lateral dimensions 50–100 nm. The observed local formations, whose density was up to 3 × 10 8 cm −2, entirely vanished from the surface after the samples were vacuum-annealed at temperatures above 300 °C. Using a direct method, electron beam microanalysis, we have determined that the defects of the hillock type includes oxygen and excessive As, while the “pits” proved to be identical in their chemical composition to InAs. Vacuum anneals were found to cause a decrease in As surface concentration relative to In on InAs surface, with a concomitant rise of surface recombination rate.