Inhomogeneous barrier height effect on the current-voltage characteristics of a W/4H-Sic Schottky diode

摘要

Silicon carbide (SiC) is an important semiconductor material used in power electronics. Due to its high hardness and brittleness. The SILVACO-TCAD numerical simulator is used to calculate the I-V characteristic of the Schottky diode (W/4H-SiC) in the temperature range of 303-448 K. This is to study the effect of temperature on the I-V curves and assess the main parameters that characterize the Schottky diode such as the ideality factor, the height of the barrier and the series resistance. The I-V characteristics are analyzed on the basis of standard thermionic emission (TE) theory and the inhomogeneous barrier heights (BHs) assuming a Gaussian distribution. It is shown that the ideality factor decreases while the barrier height increases with increasing temperature, on the basis of TE theory. Furthermore, the homogeneous BH value of approximately 1.48 eV for the device has been obtained from the linear relationship between the temperature-dependent experimentally effective BHs and ideality factors. The modified Richardson plot, according to inhomogeneity of the BHs, has a good linearity over the temperature range. The evaluated Richardson constant A* was 141.86 A·cm^-2·K^-2, which is close to the theoretical value of 146 A·cm^-2·K^-2 for n-4H-SiC. The temperature dependence of the I-V characteristics of the W/4H-SiC Schottky diode have been successfully explained on the basis of thermionic emission (TE) mechanism with Gaussian distribution of the Schottky barrier heights (SBHs). Simulated I-V characteristics are in good agreement with the measurements [Boussouar L et al. Microelectronic Engineering Vol. 88, pp. 969-975, 2011]. The barrier height obtained using Gaussian Schottky barrier distribution is 1.48 eV which is about half the band gap of 4H-SiC