Topological insulator (TI) is an unconventional phase of quantum matter possessing insulating bulk state as well as time-reversal symmetry protected Dirac-like surface state 1, 2, 3, 4, 5, 6, 7, 8, 9, 10. These findings show that the polycrystalline TI Bi 2Te 3 film working as a multifunctional photodetector can not only detect the light intensity, but also measure the polarization state of the incident light, which is remarkably different from conventional photodetectors that usually only detect the light intensity. It turns out that the theoretical results are in nice qualitative agreement with the experiment. To pursue the physical origin of the polarization dependent photocurrent, we establish the basic TI surface state model to treat the light irradiation as a perturbation and we adopt the Boltzmann equation to calculate the photocurrent. This photocurrent is linearly dependent on both the light intensity and the applied bias voltage. Herein, we report the first experimental observation of novel polarization dependent photocurrent of photodetectors based on the TI Bi 2Te 3 film under irradiation of linearly polarized light. This intriguing gapless surface state is theoretically predicted to exhibit many exotic phenomena when interacting with light and some of them have been observed. Three dimensional Z 2 Topological insulator (TI) is an unconventional phase of quantum matter possessing insulating bulk state as well as time-reversal symmetry-protected Dirac-like surface state, which is demonstrated by extensive experiments based on surface sensitive detection techniques.

Polarized light intensity equation