Schottky barrier height modification of metal/4H-SiC contact using ultrathin TiO2 insertion method

Abstract

The fabrication processes, electrical characteristics, and reliability of the Schottky barrier diodes (SBDs) on an n-type 4H-silicon carbide (SiC) substrate are investigated. To modulate the Schottky barrier height (SBH), titanium dioxide (TiO2) is inserted at the interface between the metal and the SiC substrate. Ni, Mo, Ti, and Al are chosen to form SBDs. The maximum SBH modulation of 0.3 eV is obtained with a 5-nm-thick TiO2 layer. The SBH pinning factors of the SBDs without TiO2 insertion and with 2-nm-thick TiO2 insertion are similar. Therefore, the mechanism of the SBH modulation is attributed to the interface dipole-induced potential drop. Finally, the reliability of the SBD with TiO2 insertion is evaluated. The SBH, ideality factor, and reverse leakage current are stable after high forward current stress at 300A/cm(2) for 15000 s. This work provides a simple method to modulate the SBH on SiC and is feasible for SBD application. (C) 2014 The Japan Society of Applied Physics