GaAs Deposition on the (100) and (110) Planes of Gold by Electrochemical AtomicLayer Epitaxy (ECALE). A LEED, AES and STM Study

摘要

Preliminary studies on the deposition of GaAs by electrochemical atomic layerepitaxy (ECALE) were performed. ECALE is based on the alternated underpotential deposition (UPD) of atomic layers of different elements to form a compound. Oxidative UPD of As and reductive UPD of Ga on the low-index planes of gold were studied using Auger electron spectroscopy (AES), low energy electron diffraction (LEED), scanning tunneling microscopy (STM) and coulometry. AES and LEED were performed in an ultrahigh vacuum (UHV) surface analysis instrument interfaced to an electrochemical cell in an antechamber. This instrument configuration allowed the electrochemical treatment of the samples and their subsequent analysis in UHV without the need to transfer the samples through air. STM was performed under nitrogen at atmospheric pressure. AES and coulomet were used for surface composition analysis while LEED and STM provided structural information. The substrate was a gold single-crystal electrode with three oriented faces, each to a different low-index plane. Oxidative UPD of arsenic was observed only on the (100) and (110) faces. The resulting structures were a Au(100) (2X2)-As at 1/4 coverage and a Au(110)c(2X2)-As at 1/2 coverage. GaAs, Electrodeposition, ALE, Gold Single Crystals.