关键词: SiC MOSFET, 电流传输机制, FN隧穿, 势垒高度

Abstract: The forward and reverse gate leakage current transport mechanisms of SiC MOSFET have been investigated by fitting the temperature dependent current-voltage experimental data. 1) The gate currents under high forward and reverse bias are dominated by FN (Fowler-Nordheim) tunneling mechanism, and the electron barrier heights of SiC/SiO₂ interface are 2.58-2.69 eV and 3.02-3.26 eV, respectively. 2) Under high forward bias, the gate current increases with temperature. This behavior is explained as following: with increasing temperature, the atoms move randomly around their equilibrium points, that is, the height of the saddle point begins to fluctuate. Due to the exponential relationship between the current density and the barrier height in the FN transport model, the increase trend of the current density when the barrier height decreases is much higher than the decrease of it when the barrier height increases. So as the temperature increases, the gate current increases gradually, and the average barrier height decreases. 3) Under high reverse bias, owing to the large number of electron-hole pairs generated by impact ionization, the concentration of holes injected into the gate oxide of JFET region increases, and the barrier height decreases further. Therefore, the barrier height decreases more rapidly with increasing temperature under high reverse bias.

Key words: SiC MOSFET, current transport mechanism, FN tunneling, barrier height