A hybrid 6H-SiC temperature sensor operational from 25°C to 500°C

Abstract

6H-SiC buried-gate n-channel depletion-mode junction field-effect transistors (JFETs) were characterized from 25/spl deg/C to 350/spl deg/C in terms of transconductance (g/sub m/), pinchoff voltage (V/sub P/), output resistance (r/sub o/), input resistance (R/sub in/), drain-to-source current at zero gate-to-source voltage (I/sub DSS/), gate-to-source reverse biased leakage current (I/sub GSS/), off-state drain-to-source current (I/sub DSS(off)/), and noise power spectral density (S/sub V/). The 6H-SiC JFET's were used in a hybrid temperature monitoring circuit (tested from -196/spl deg/C to 500/spl deg/C) fabricated at Auburn University for use in numerous industrial applications. Simulation program with integrated circuit emphasis (SPICE) simulations of the temperature monitoring circuit's output voltage corresponded well with measured data as a function of temperature. Linear regression (LR) analysis of measured data revealed a notably sensitive (/spl sim/2.3 mV//spl deg/), and an eminently linear (correlation coefficient =-0.0996...over 25/spl deg/C to 500/spl deg/C range) relationship between the measured output voltage and temperature. Below -50/spl deg/C, the output became nonlinear, presumably from carrier freeze-out effects. To the best of our knowledge, this represents the first successful implementation of SiC active devices into a temperature sensor which demonstrated stable operation up to 500/spl deg/C.