Topological Insulator Based Dual State Photo‐Switch Originating Through Bulk and Surface Conduction Channels. Issue 9 (6th August 2018)

• Record Type: Journal Article
• Authors: Bhattacharyya, Biplab; Gupta, Anurag; Senguttuvan, Thanikachalam Devarajan; Ojha, Vijay Narain; Husale, Sudhir
• Is Part Of: Physica status solidi. Volume 255:Issue 9(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-08-06
• Subjects: low temperature -- negative photoresponse -- topological insulators -- topological surface states -- voltage responsivity; Solid state physics -- Periodicals; Solids -- Periodicals; Atomic structure -- Periodicals; 530.41
• DOI: 10.1002/pssb.201800340
• Languages: English
• ISSNs: 0370-1972

Abstract

Abstract : Topological insulators are novel electronic materials, where time reversal symmetry protects the spin‐polarized surface states from backscattering. Although, the bulk offers a trivial semiconducting response to incident light, but the metallic surface states exhibit interesting electrical response towards the incident radiation, such as polarization dependent surface photocurrent and topological phase transitions. Here, we study the temperature dependent near‐infrared photoresponse in bismuth selenide (Bi2 Se3 ) nano‐flakes. A very good photo‐sensitivity to near‐infrared 800 nm wavelength is observed for the temperature range 300–2 K. Voltage responsivity at 2 K (1.481 × 10 10 VW −1 ) is estimated to be four‐order greater than at 300 K (2.095 × 10 6 VW −1 ) and is comparatively much higher than the previously reported values of voltage responsivity in other materials. Interestingly, we also find the temperature dependent existence of both positive and negative photoresponse in our device. An anomalous photoresponse reversal is observed at 2 K, where resistance of the nano‐flake increases under light illumination. We propose that this phenomenon is due to the topological surface states, which have dominant transport contribution at very low temperatures. These observations establish the fact that topological insulators can be further engineered to develop a dual state photo‐switch, by manipulating the bulk and surface state conduction contribution. Abstract : Temperature dependent opto‐electronic study of Bi2 Se3 nanoflakes demonstrates the existence of two different kinds of conduction channels (surface states and bulk). The origin of negative photoresponse due to topological surface states suggests the possibility of exciting electron–photon coupled systems. Also, the ultrahigh light sensitivity of topological insulators based nanodevices at low temperatures may find useful application as single‐photon detectors.