Investigation of 12 μm 4H-SiC epilayers for radiation detection and noise analysis of front-end readout electronics

Abstract

Schottky barrier radiation detectors were fabricated on 12 μm n-type 4H-SiC epitaxial layers grown on a 4° off-axis highly doped 4H-SiC substrate (0001). Schottky barrier junction properties were characterized through current-voltage (I-V) and capacitance-voltage (C-V) measurements. A diode ideality factor of 1.29 and Schottky barrier height of 1.10 eV were determined from the forward I-V characteristics using a thermionic emission model. A built-in potential of 1.91 V and effective carrier concentration of 1.03 × 10 15 cm -3 was calculated from a Mott-Schottky plot of the C-V measurements. Radiation detector performance was evaluated by alpha pulse height spectroscopy (PHS) in terms of energy resolution expressed in full-width at half maxima (FWHM) and charge collection efficiency (CCE). The energy resolution was determined to be 166 keV with a CCE of 22.6% for 5.486 MeV alpha particles. Deep level transient spectroscopy (DLTS) measurements were carried out to investigate the deep levels in the detector active region. An electrically active defect level Z 1/2 related to carbon vacancies was identified and characterized. The concentration and capture cross-section of Z 1/2 were determined to be 1. 58 × 10 12 cm -3 and 9.12 × 10 -16 cm 2 , respectively. Electronic noise analysis in terms of equivalent noise charge (ENC) was carried out to study the effect of various noise components that contribute to the total electronic noise in the detection system.