Imaging and spectrometric performance of SiC Timepix3 radiation camera

Abstract

A Schottky barrier radiation detector and pixel imaging sensor fabricated from epitaxially grown SiC semiconductor were analyzed. The detector was based on an 80 μm thick epitaxial SiC layer. Capacitance-voltage measurement was performed to study the thickness of the space charge region of the detector as a function of applied bias. The results showed that the detector was completely depleted at a reverse bias higher than 300 V. The impurity concentration profile was also calculated, which indicated a net impurity concentration below 1.5×1014 cm-3. A prototype of a SiC Timpix3 radiation camera was fabricated, and its energy resolution was investigated using the 241Am radioisotope. The camera exhibited an energy resolution of 4.5 keV for 60 keV gamma photons. X-ray fluorescence photons (from 14 keV to 22 keV) were detected with a resolution below 2.0 keV. The imaging quality of the camera was investigated using a test object. The prototype showed a high-quality image performance with a stable count rate, which was determined from uniform intensity profiles extracted from parts of the test object image. A disadvantage of this prototype is that the radiation hits the detector from the side of the substrate and only then it reaches its active SiC epitaxial layer. This represents a dead layer that reduced the detection efficiency of X-rays below 10 keV.