Piezo-optoelectronic coupling in heterojunctions for self-powered and ultrasensitive pressure sensing

Abstract

It is highly desirable to discover sensing mechanisms for developing self-powered and ultrasensitive pressure sensing. Here, we report that the piezo-optoelectronic coupling in a n+-3C-SiC/p-Si heterojunction not only enables energy harvesting but also features massive strain sensitivity. To demonstrate the proof of the concept, a pressure sensing device is developed with active and reference electrodes arranged on SiC along strain-sensitive [100] and strain-insensitive [110] orientations, respectively. Under the illumination of 637-nm laser at 2.0 mW, experimental results show the great response of the photogenerated voltage to the change in both static and dynamic pressures. Gauge factor is found to be −670.2 which is much larger than the highest gauge factor of n-type 3C-SiC. The underlying physics behind is the strain modulation on the effective mass and energy level of photogenerated charge carriers. This results in the change in carrier concentration detected by the electrodes along the strain-sensitive and strain-insensitive orientations. These findings could contribute significantly to the development of self-powered mechanical sensors using solid-state electronics.