Analysis of the inhomogeneous barrier and phase composition of W/4H-SiC Schottky contacts formed at different annealing temperatures**Project supported by the Opening Project of Key Laboratory of Microelectronics Devices & Integrated Technology, Institute of Microelectronics, Chinese Academy of Sciences and the National Key Research and Development Program of China (Grant No. 2016YFB0100601).

Abstract

The electrical characteristics of W/4H-SiC Schottky contacts formed at different annealing temperatures have been measured by using current–voltage–temperatures (I–V–T) and capacitance–voltage–temperatures (C–V–T) techniques in the temperature range of 25 °C–175 °C. The testing temperature dependence of the barrier height (BH) and ideality factor (n) indicates the presence of inhomogeneous barrier. Tung’s model has been applied to evaluate the degree of inhomogeneity, and it is found that the 400 °C annealed sample has the lowest T0 of 44.6 K among all the Schottky contacts. The barrier height obtained from C–V–T measurement is independent of the testing temperature, which suggests a uniform BH. The x-ray diffraction (XRD) analysis shows that there are two kinds of space groups of W when it is deposited or annealed at lower temperature (≤ 500 °C). The phase of W2C appears in the sample annealed at 600 °C, which results in the low BH and the high T0. The 500 °C annealed sample has the highest BH at all testing temperatures, indicating an optimal annealing temperature for the W/4H-SiC Schottky rectifier for high-temperature application.