4H-SiC Schottky diodes with Ni2Si contacts for X-ray detection

Abstract

Abstract 4H-SiC Schottky photodiodes , with 25 μ m epitaxial layers, employing thin (20 nm) Ni2Si Schottky contacts, were investigated for high temperature photon counting X-ray spectroscopy. Important X-ray photodiode detector parameters were extracted from electrical characterization within the temperature range 160 °C to 0 °C. The devices were found to be fully depleted at an applied electric field of 20 kV/cm; a leakage current density of 33 nA cm -2 ± 1 nA cm−2 at 160 °C, was measured for one of the devices. The detectors were subsequently connected to low-noise photon counting readout electronics and investigated for their spectral performance at temperatures up to 100 °C. With the charge-sensitive preamplifier operated at the same temperature as the detector the best energy resolution ( Full Width at Half Maximum at 5.9 keV) obtained decreased from 2.20 keV ± 0.04 keV (120 e − rms ± 2 e − rms) at 100 ∘ C to 1.20 keV ± 0.03 keV (65 e - rms ± 2 e − rms) at 0 ∘ C. The dominant source of noise broadening the 55 Fe X-ray photopeak was found to be the dielectric noise, except for the spectra accumulated at 100 °C and long shaping times (> 6 μ s ), in those case the main source of photopeak broadening was the white parallel noise.