Thermo-phototronic\nEffect in Double Semiconductor\nHeterostructures for Highly Sensitive Self-Powered Sensors

Understanding\nthe sensing mechanism and the structure–property\nrelationship of self-powered, ultrasensitive photodetectors and temperature\nsensors is essential for their development. In this study, we report\nthe thermo-phototronic effect observed in double semiconductor heterostructures\ncapable of light harvesting and ultrasensitive temperature sensing.\nTo demonstrate the advances of using the double heterostructure, we\nconducted a comparative study with a single heterostructure of highly\ndoped n-3C-SiC/p-Si to understand the light harvesting capability\nand sensing performance. Our results show that the double n-3C-SiC/p-Si\nheterostructure outperformed the single counterpart in both photovoltage\ngeneration and sensitivity, confirming that the structural design\nsignificantly impacts the sensing performance of the devices. Under\n 7.5 mW/cm<sup>2</sup> illumination, the measured voltage in the double\nstructure changed by 21 mV under a 0.2 K temperature gradient, corresponding\nto an ultrahigh sensitivity of 110 mV/K. This sensitivity is more\nthan 300 times higher than that of 0.3 mV/K observed in the single\nheterostructure. The underlying physics is attributed to the structural\ndesign of the double n-3C-SiC/p-Si heterostructure that controls charge\ncarrier diffusion from the illuminated electrode to the other, resulting\nin a high photovoltage. These findings demonstrate that using the\ndouble n-3C-SiC/p-Si heterostructures can significantly enhance the\nsensitivity compared with using the single heterostructures, thereby\ncontributing significantly to the development of self-powered photodetectors\nand temperature sensors.