4H-SiC epitaxial Schottky detectors: deep-level transient spectroscopy (DLTS) and pulse height spectroscopy (PHS) measurements

摘要

Schottky barrier radiation detectors have been fabricated on n-type 4H-SiC epitaxial layers (Eg = 3.27 eV at 300 K) grownon low-resistive n-type 4H-SiC bulk substrates. Current-voltage (I-V) and capacitance-voltage (C-V) measurements werecarried out, and using a thermionic emission model, Schottky barrier height of ～1.42 eV was obtained. Capacitance modedeep level transient spectroscopy (DLTS) revealed the presence of deep levels along with two shallow level defects relatedto titanium impurities (Ti?) and an unidentified deep electron trap located at 1.42 eV below the conduction bandminimum. The concentration of the lifetime killer Z1/2 defect was found to be ～1013 cm-3. A 0.1 μCi 241Am radiation sourcewas used to investigate the detector performance including charge collection efficiency (CCE) by pulse heightspectroscopy (PHS), and an energy resolution of ～ 0.38% full-width half maxima (FWHM) was observed for alphaparticles at ～ 5447 keV. The average diffusion length (Ld) of holes (minority carriers) were calculated to be ～ 13.6 μmusing a drift-diffusion model and MATLAB code. An electronic noise analysis of front-end readout electronics in termsof equivalent noise charge revealed that the white series noise due to the detector capacitance has substantial effect ontheir spectroscopic detection performance.