Metal-insulator-SiC Schottky structures using HfO2 and TiO2 dielectrics

Abstract

Metal-Insulator-Semiconductor Schottky diodes were fabricated on SiC, as a potential use for particle detectors. Nickel was used as Schottky and back ohmic contacts. The dielectrics HfO2 and TiO2 were investigated as insulating layers and deposited by Atomic Layer Deposition, with thicknesses of 1, 2 and 4nm. Current-Voltage curves were extracted from the diodes, varying the measurement temperature (297K–373K). Apparent and real Schottky Barrier Heights (SBHapparent and SBHreal), ideality factor η and insulating layer thicknesses were extracted from the I-V curves. Thicker insulating layers produce higher η and reduce the SBHreal value, for both dielectrics. An interfacial layer of silicon oxycarbide with thickness of 0.2nm was estimated for all diodes. The SBHreal goes from 1.22V to 0.66V and from 1.26 V to 0.59 V, for thicknesses of 1nm and 4nm of HfO2 and TiO2, respectively. The reverse currents for all structures at 40V of bias are of order of tens of pA at room temperature.