Detection of ultraviolet radiation using silicon carbide P-N junctions

The photovoltaic response of silicon carbide p-n junctions has been used for the detection of ultraviolet radiation at high temperatures. The wavelength at which peak response occurs is dependent on the junction depth. With junction depths of ten microns and one micron, the wavelengths at peak response are near 3800Å and 2850Å respectively at room temperature. The wavelength at peak response increases by 0.4 to 0.7Å/deg and the photovoltage of the detector decreases with increasing temperatures. However, a number of detectors have open circuit photovoltages up to 100 mV at 800°K. As the wavelength of the incident radiation increases to near the band edge of silicon carbide, the photovoltage of the shallow junction devices becomes non-detectable. Both the peak wavelength as a function of junction depth and the variation of the peak wavelength with temperature can be quantitatively explained by considering the wavelength dependence of the absorption coefficient in silicon carbide below the band edge.