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STUDIES OF OHMIC CONTACT AND SCHOTTKY BARRIERS ON Au-Ge/GaAs AND Au-Ti/GaAs

R. V. Ghita1,* , C. Logofatu1, C. Negrila1, A. S. Manea1, M. Cernea1, M. F. Lazarescu1

Affiliation

  1. National Institute of Materials Physics, P. O. Box MG 7, Magurele, Bucharest, Romania

Abstract

Gallium Arsenide (GaAs) has increasingly become an important compound-semiconductor material suited for high speed digital circuits, microwaves and detectors for high energy physics. For the fabrication of ohmic contacts on GaAs (semi-insulating- SI) wafers with characteristics as: Cr doped, (100) oriented, and r~106-107 Wcm, has been used alloyed contact Au-Ge. The ohmic film was deposited in a high vacuum chamber (10-8 Torr), on a plasma etched surface of GaAs, followed by a rapid thermal annealing (RTA) at 450C in low vacuum. For the fabrication of the rectifying contact- respectively the Schottky diode structure, we have used the same GaAs substrates. The wafers were degreased in a standard cleaning procedure, followed by a chemical etching. The Au-Ti contact has been deposited by thermal evaporation in vacuum (10-6 torr) followed by a RTA procedure at 300-320 C. The carrier transport mechanisms through M/S interface are strongly influenced by the doping concentration in the semiconductor and temperature. There are presented the experimental I-V characteristics for selected samples in dark and illumination conditions. Schottky barriers height on Au-Ti/GaAs was 0.7325 V in accord with mean values on n and p type GaAs (0.5-0.8 V). The aim of this work is to fabricate a competitive X-ray detector..

Keywords

GaAs (SI), Metal deposition, Ohmic contact, Schottky contact.

Submitted at: Oct. 11, 2005
Accepted at: Nov. 24, 2005

Citation

R. V. Ghita, C. Logofatu, C. Negrila, A. S. Manea, M. Cernea, M. F. Lazarescu, STUDIES OF OHMIC CONTACT AND SCHOTTKY BARRIERS ON Au-Ge/GaAs AND Au-Ti/GaAs, Journal of Optoelectronics and Advanced Materials Vol. 7, Iss. 6, pp. 3033-3037 (2005)