Diffusion Length in n-Doped 4H Silicon Carbide Crystals Detected by Alpha Particle Probe

Abstract

The achievement of nuclear detectors in Silicon Carbide imposes severe constraints on the electronic quality and thickness of the material due to the relatively high value of the energy required to generate an electron-hole pair (7.8 eV) in this material compared to the value for Si (3.6 eV). In this work, 4H-SiC charged particle detectors were realised using epitaxial layers of n-type doping as active region. The thickness of the epilayer is always below 80 μm with a net doping concentration in the range of 8 x 1013 to 1016 cm-3. These properties allowed the fabrication of Schottky diodes that operate well as radiation detectors. At low doping concentration, the epilayer is totally depleted at quite low reverse bias (≈ 50 V), thereby obtaining the maximum active volume.