A High-Bandwidth, Spectrally Broad Photodetector Based on Optically-Induced Seebeck Effect

Abstract

In this thesis, we engineered a fast response high bandwidth self-powered infrared photodetector based on optically induced Seebeck effect in Cd3As2 operating at room temperature. The metal-semimetal-metal device was subject to transient photo-response tests using high-frequency lock-in modulation techniques. Our photodetector demonstrates a Seebeck voltage under the off-center illumination of a laser with the wavelength of 1064 nm, due to a temperature gradient. The photocurrent is readily registered at a modulation frequency of 6 kHz and further analysis indicates the sensor intrinsic bandwidth is predicted to approach the terahertz range. The responsivity of the sensor is 0.27 mA/W at room temperature and the photocurrent is found to be dependent on the modulation frequency and the optical power. Our study reveals that Cd3As2 is a promising candidate for a fast response, high bandwidth spectrally broad device applications in optoelectronics.