A HIGH OPTICAL-GAIN BETA-SIC BULK-BARRIER PHOTOTRANSISTOR FOR HIGH-TEMPERATURE APPLICATIONS

A high optical-gain beta-SiC phototransistor (PT) with a bulk-barrier structure has been fabricated on a silicon substrate. It demonstrated high optical gains of 145 at 25 degrees C and 106 at 250 degrees C, un der a 10-V bias and 10-mu W incident optical power with a wavelength o f 500 nm. The high optical gains at elevated temperatures are attribut ed to not only the excellent high-temperature properties of SIC materi als, but also the bulk-barrier structure, in which the formed potentia l barrier, the short base region and an effect of thinning the quasi-n eutral base region to zero thickness lead to a greatly enhanced curren t gain. The developed beta-SiC built-barrier PT possesses a potential for high-temperature high-gain optical-sensing applications.