Thermo-phototronic Effect in Double Semiconductor Heterostructures for Highly Sensitive Self-Powered Sensors

Abstract

Understanding the sensing mechanism and the structure–property relationship of self-powered, ultrasensitive photodetectors and temperature sensors is essential for their development. In this study, we report the thermo-phototronic effect observed in double semiconductor heterostructures capable of light harvesting and ultrasensitive temperature sensing. To demonstrate the advances of using the double heterostructure, we conducted a comparative study with a single heterostructure of highly doped n-3C-SiC/p-Si to understand the light harvesting capability and sensing performance. Our results show that the double n-3C-SiC/p-Si heterostructure outperformed the single counterpart in both photovoltage generation and sensitivity, confirming that the structural design significantly impacts the sensing performance of the devices. Under 7.5 mW/cm2 illumination, the measured voltage in the double structure changed by 21 mV under a 0.2 K temperature gradient, corresponding to an ultrahigh sensitivity of 110 mV/K. This sensitivity is more than 300 times higher than that of 0.3 mV/K observed in the single heterostructure. The underlying physics is attributed to the structural design of the double n-3C-SiC/p-Si heterostructure that controls charge carrier diffusion from the illuminated electrode to the other, resulting in a high photovoltage. These findings demonstrate that using the double n-3C-SiC/p-Si heterostructures can significantly enhance the sensitivity compared with using the single heterostructures, thereby contributing significantly to the development of self-powered photodetectors and temperature sensors.