TA/GAAS SCHOTTKY BARRIERS PRODUCED BY INSITU SPUTTER ETCHING, RF-MAGNETRON SPUTTERING OF TA, AND ITS THERMAL-OXIDATION

A method for preparation of high quality Ta/GaAs Schottky barriers using of planar magnetron sputtering is presented. Thermally stimulated recovery of structural defects induced on GaAs by planar magnetron sputtering of Ta is studied and optimal time and temperature of this treatment are determined. Typical values of the ideality factors and barrier heights obtained on thermally treated structures are n = 1.03 to 1.07 and Φb = 0.7 eV, respectively. The oxidation of thermally treated Ta in the atmosphere of air, oxygen, and argon undeliberately doped with O2 is studied. It is demonstrated that at the optimum temperature for thermal treatment −400 °C and times up to 100 min – relatively thick oxide layers of about 80 nm can be formed. A model of the Ta/GaAs structures obtained under the conditions above described is presented. According to this model the Schottky barrier edge is buried in both, Ta2O5 and native GaAs oxides thus resulting in very small leakage currents — typically 10−9 A. Copyright © 1990 WILEY‐VCH Verlag GmbH & Co. KGaA