Photovoltaic Effect-Based Multifunctional Photodetection and Position Sensing Using a 3C-SiC/Si Heterojunction

With the increasing interest in the photovoltage generation mechanisms in different materials and structures, this study presents the first investigation of multifunctional light detection and position sensing using semiconductor heterojunctions based on the photovoltaic effect. The proposed sensing device was fabricated by using a 3C-SiC/Si heterojunction with top and bottom electrodes designed to collect the photogenerated charge carriers crossing the junction. The generated photovoltage was monitored to both detect the emergence of incident light and sense the light position. The photoresponsivity and position sensitivity were studied under different laser powers and wavelengths at zero bias, and the results showed a great photoresponsivity and a highly linear position sensitivity of 376.6 mV/mW and 179.2 mV/mm, respectively, under the illumination of 637 nm laser wavelength with 1 mW power and 130 μm beam diameter. A reverse current was then introduced to improve further the performance of the proposed SiC/Si sensing device. Under the optimal current of 0.3 mA, the photoresponsivity and position sensitivity were increased substantially to 1384.2 mV/mW and 757.6 mV/mm under the above laser wavelength and power, presenting substantial 3.6 and 4.2 times improvement, respectively. The observed phenomena were explained in detail by the transportation of photogenerated charge carriers under illumination, including thermionic emission and drift mechanisms in the out-of-plane direction and diffusion mechanism in the in-plane direction. The successful proof of concept in this study represents the first step toward developing multifunctional photodetection and position sensors using semiconductor heterostructures based on the photovoltaic effect.