The electrical properties and thermal stability of WNx/GaAs contacts where WNx is formed by reactive sputtering of W are investigated. The results show that contacts have good electrical properties and thermal stability provided that the partial pressure of nitrogen gas during sputtering does not exceed certain limits. Excess nitrogen in WNx film degrades contact properties. The formation of W and W2N phases, trapping of excess nitrogen atoms at the interface and the possible formation of GaAsxN1-x compound at the interface, with x being a function of annealing temperature, were used to explain the observation. References: 12
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