High Responsivity Analysis of 4H-SiC Phototransistor

Abstract

The performance of a 4H-SiC n-p-n phototransistor with a 30-μm thick collector under different bias voltages, light intensities, and temperatures is meticulously studied in this letter. The responsivity of the device to 360-nm incident light is improved to 2.02 × 10⁴ A/W with 37 V bias voltage. Bias voltage and incident light intensity have a synergistic effect on the device's responsivity. As the bias voltage increases, the responsivity of the device increases drastically at low incident light intensities. In contrast, the increasing trend slows down at high intensities due to the increased concentration of carriers in the base region, causing the neutral region to widen. The device is capable of responding linearly to 360 nm light with an intensity range exceeding 5 orders of magnitude at 5 V. High-temperature detection characterization indicates that the device biased at 21 V has a responsivity of 2.5 × 10⁴ A/W at 453 K, which provides experimental evidence for the 4H-SiC phototransistor's high-temperature detection ability.