High performance broadband bismuth telluride tetradymite topological insulator photodiode

Abstract

A small bulk gap and the presence of Dirac electrons due to conductive surface states make tetradymite topological insulators promising candidates for optoelectronic devices. In this work, we demonstrate a highly responsive Bi 2 Te 3 -Si heterostructure photodiode. The thermally evaporated Bi 2 Te 3 film, exhibiting a nanocrystalline nature, shows p-type doping behavior due to bismuth vacancies. As a result of the work function difference between Bi 2 Te 3 and p-type Si, charge transfer occurs and a Schottky barrier is formed. Using the thermionic emission model, the barrier height (Φ B ) is extracted to be ∼0.405 eV. For minimizing the effect of extrinsic defects, the photodiodes were capped with graphene or Si 3 N 4 . Since graphene acts as an efficient photoexcited carrier collector, the graphene capped device outperforms the Si 3 N 4 capped device. The higher quality Bi 2 Te 3 nanocrystalline film of the Si 3 N 4 capped photodiode contributes to a one-order-of-magnitude improvement in responsivity at 1550 nm wavelength, as compared to the graphene capped photodiode. The Si 3 N 4 capped photodiode shows photoresponse even at zero bias for 1550 nm wavelength. Built-in potential due to charge transfer at the interface of Bi 2 Te 3 and Si capped with a graphene electrode exhibits the highest responsivity (8.9 A W −1 ). Broadband photodetection is observed in both types of photodiodes.

A Review on Doped/Composite Bismuth Chalcogenide Compounds for Thermoelectric Device Applications: Various Synthesis Techniques and Challenges

“…The crystal structure of prepared chalcogenides of bismuth telluride and bismuth selenides are found to crystallize in the tetradymite crystal structure. 133 A rock salt structure is observed between Bi, Te, and Se. The associated valences of Bi + (s 2 p °) and Te −2 are indicated by the differences in the electronegativity among Bi, Te, and Se.…”

Ultrafast Charge Transfer Mechanism in Van der Waals Heterostructures of Topological Insulators with 2D Materials

“…Remarkable properties of van der Waals heterostructures (vdW) of atomically thin layered materials such as graphene, transition-metal dichalcogenides (TMDs), and other topological layered materials have opened up a plethora of new avenues for fundamental and applied research. − Different applications of several such interfaces have been explored in the recent past with the help of topological layered materials and their heterostructures. ,,− It has been predicted that interfaces of other atomic layers with topological materials can bring interesting synergistic properties, and they can find applications in optoelectronics, quantum computing, and spintronics. − Moreover, recently, the assembly of graphene with certain TMDs has been proposed as a potential system for broadband photodetection . In such vdW assembly, TMDs offer a high light absorption and hence acting as an active layer in the photodetector, while graphene can enchance the photocarrier response due to its high conductivity. ,,− Graphene/Bi 2 Te 3 and graphene/Bi 2 Se 3 are some leading examples of vdW of graphene with topological materials (TM) ,,− where the graphene/Bi 2 Se 3 heterostructures induce a photogating effect coupled with the photovoltaic effect via tuneable quantum tunneling and thereby enhance the responsivity of photodetectors . However, in the graphene/Bi 2 Te 3 heterostructure, the reasons for enhanced photoresponsivity are adequate photocarrier generation and transfer of these carriers at the interface …”

Excitation of Hybrid Waveguide-Bloch Surface States with Bi2Se3 Plasmonic Material in the Near-Infrared Range

“…With the preparation and development of new materials, the performance of optical devices can be significantly improved [ 13 , 14 , 15 , 16 , 17 , 18 ]. Tetradymites have become popular due to the recently discovered topological insulator property [ 19 , 20 ]. Bismuth selenide (Bi 2 Se 3 ) has been shown as one of the potential candidates for surface plasmons [ 21 , 22 ], which holds great potential in high-performance photonic devices [ 23 , 24 , 25 ].…”