4H-SiC Schottky barrier diodes as radiation detectors: A role of Schottky contact area

Abstract

Large-area SiC Schottky barrier diodes can significantly improve the sensitivity in radiation detection due to the increased interacting SiC volume. In this work, we tested a large SiC detector with an area of 1 × 1 cm2. Extensive electrical characterization was performed at temperatures ranging from 150 K to 390 K, demonstrating the impact of barrier inhomogeneities on the electrical performance of the diode. Forward current-voltage (I-V) measurements of the diodes revealed two distinct regions caused by Schottky barrier inhomogeneity present throughout the entire temperature range. The barrier heights in the low- and high-current forward voltage regions were extracted from Richardson plots corrected for the Gaussian distribution of barrier heights, yielding values of 1.52 eV and 1.79 eV, respectively. Deep-level transient spectroscopy (DLTS) revealed only one deep-level defect, Z1/2, with an activation energy for electron emission of 0.67 eV, which was assigned to the known carbon vacancy. The DLTS study showed no correlation between electrically active defects and barrier inhomogeneity. An excellent energy resolution of 3.2 % was measured using a large area 241Am radiation source, consistent with values for small area SiC detectors that exhibited no barrier height inhomogeneities. The impact of temperature on the alpha particle radiation response was determined within a temperature range of 200 K to 390 K.