Photo-Seebeck effect in single-crystalline bismuth telluride topological insulator

摘要

Bismuth telluride is a low energy bulk bandgap topological system with conducting surface states. Besides its very good thermoelectric properties, it also makes a very good candidate for broadband photodetectors. Here, we report the temperature-dependent photo-Seebeck effect in a bulk single crystalline bismuth telluride. Upon light illumination, an electrically biased sample shows distinguishable contributions in the measured current due to both the Seebeck effect and the normal photo-generated carriers within a narrow layer of the sample. The detailed experiments are performed to elucidate the distinction between the Seebeck contribution and the photogenerated current. The temperature dependence of the photocurrent without Seebeck contribution shows a sign reversal from negative to positive at a specific temperature depending on the wavelength of photoexcitation light.