Ni/Al<inf>2</inf>O<inf>3</inf>/4H-SiC Schottky diodes

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 dielectric Al 2 O 3 was investigated as insulating layer and deposited by Atomic Layer Deposition, with thicknesses of 1, 2 and 4 nm. Current-Voltage curves were extracted from the diodes, varying the measurement temperature (297 K–373 K). Apparent and real Schottky Barrier Heights (SBH), ideality factors η and insulating layer thicknesses were extracted from the I-V curves. Thicker insulating layers produce higher η and reduce the real SBH value. An interfacial layer of silicon oxycarbide with thickness of 0.2 nm was estimated for the diodes. The real SBH goes from 1.32 V to 0.87 V for thicknesses of 1 nm and 2 nm of Al 2 O 3 , respectively. The diode with 4 nm of Al 2 O 3 has not presented Schottky characteristics. The reverse currents for the diodes are in the range of hundreds of pA, making them suitable for particle detectors. We also show an application of the MIS structure to be used as He++ particle detector in Rutherford Backscattering Spectroscopy experiment.