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XPS study of Ti/oxidized GaAs interface

R. V. GHITA1,* , C. LOGOFATU1, C. NEGRILA1, A. S. MANEA1, M. CERNEA1, V. CIUPINA2, M. F. LAZARESCU1

Affiliation

  1. National Institute of Materiasl Physics P.O. Box MG 7, Magurele, Bucharest, Romania
  2. Department of Physics, “Ovidius” University of Constanta, RO-8700, Constanta, Romania

Abstract

X-Ray Photoelectron Spectroscopy (XPS) analysis was performed on Ti/oxidized GaAs. This interface is prepared by chemical etching in a mixture of reagents, followed by a vacuum deposition of a nanometer Ti layer. The surface sensitivity of XPS (typica ly 40-100 Å), makes the technique ideal for the measurements of oxidation states and oxide layer thickness on III-V compounds. The study of Ti/oxidized GaAs put into evidence a lack of stoichiometry at the semiconductor surface due to the presence of a volatile element (As). At the interface Ti/Oxide/n-GaAs common oxides are present: Ga2O3, As2O3 and As2O5, together with titanium oxide. The XPS spectra recorded on the sample surface sputtered with 5 keV Ar+ ions (in two steps: t = 15 min, t = 45 min) were analyzed using SDP subroutines program facilities. The As signal at the interface after t = 15min plasma etching is related to GaAs, As2O3 and over 40% from a GaAs oxidation complex or due to inter metallic oxide of Ti. After the last plasma etching at the surface of GaAs the stoichiometry was demonstrated: the signal of As and Ga arises commonly from GaAs. It was remarked a broader titanium line profile, which arises from titanium oxide and from different intermediate states at the interface..

Keywords

X-Ray photoelectron spectroscopy, Chemical etching, Oxidation states, Plasma etching.

Submitted at: Oct. 14, 2005
Accepted at: Jan. 26, 2006

Citation

R. V. GHITA, C. LOGOFATU, C. NEGRILA, A. S. MANEA, M. CERNEA, V. CIUPINA, M. F. LAZARESCU, XPS study of Ti/oxidized GaAs interface, Journal of Optoelectronics and Advanced Materials Vol. 8, Iss. 1, pp. 31-36 (2006)