First Principle Defect Analysis in 150 µm 4H-SiC Epitaxial Layer Schottky Barrier Detectors

Abstract

High resolution Schottky barrier detectors (SBDs) were fabricated on 150 µm thick 4H-SiC epilayers using a proprietary device design. Electrical properties of the SBD junctions were characterized by temperature-dependent current-voltage (I-V- T) measurements which showed ultra-low leakage current densities lower than 100 pA cm−2at -150 V and remained below 1 µ A.cm−2 even at 600K. Electrically active deep levels present in the epilayers were identified and characterized by deep level transient spectroscopy (DLTS) which showed the presence of three deep levels - Ti(c), Z1/2 and EH6/7- with low concentrations (~1011 cm−3). The energy levels were investigated theoretically by density functional theory (DFT) calculations on intrinsic vacancies and titanium point defects. Pulse height spectra (PHS) were collected using a 241Am alpha source and a percentage energy resolution of 0.55% at 5486 keV was obtained. Further analysis of the forward bias I-V- T showed an improvement in ideality factor and barrier height at elevated temperature revealing the improvement of detection performance at higher temperature.