High temperature characteristics of amorphous TiWSixnonalloyed ohmic contacts to GaAs

摘要

This article reports on amorphous (agr;) nonalloyed TiWSixohmic contacts onnhyphen;GaAs using an intervening gradedhyphen;bandhyphen;gap layer of InxGa1minus;xAs grown by the low pressure organometallic chemical vapor deposition method. The metal silicide contacts consisted of extremely thin alternating layers of TiW and Si sequentially deposited by rf magnetron sputtering to a total thickness of 500 Aring;. The ashyphen;deposited contacts exhibited ohmic behavior without requiring posthyphen;deposition heat treatment, and yielded specific contact resistivity values as low as 9times;10minus;7OHgr;thinsp;cm2. These contacts were shown to be stable and retained excellent surface morphology after 600thinsp;deg;C thermal annealing. Rutherford backscattering and Auger electron spectroscopy investigations revealed no apparent interdiffusion at the metal/semiconductor interface under the above annealing conditions.