The effect of charged particle irradiation on the transport properties of bismuth chalcogenide topological insulators: a brief review.

Topological insulators (TIs) offer a novel platform for achieving exciting applications, such as low-power electronics, spintronics, and quantum computation. Hence, the spin-momentum locked and topologically nontrivial surface state of TIs is highly coveted by the research and development industry. Particle irradiation in TIs is a fast-growing field of research owing to the industrial scalability of the particle irradiation technique. Unfortunately, real three-dimensional TI materials, such as bismuth selenide, invariably host a significant population of charged native defects, which cause the ideally insulating bulk to behave like a metal, masking the relatively weak signatures of metallic topological surface states. Particle irradiation has emerged as an effective technique for Fermi energy tuning to achieve an insulating bulk in TI along with other popularly practiced methods, such as substitution doping and electrical gating. Irradiation methods have been used for many years to enhance the thermoelectric properties of bismuth chalcogenides, predominantly by increasing carrier density. In contrast, uncovering the surface states in bismuth-based TI requires the suppression of carrier density via particle irradiation. Hence, the literature on the effect of irradiation on bismuth chalcogenides extends widely to both ends of the spectrum (thermoelectric and topological properties). This review attempts to collate the available literature on particle irradiation-driven Fermi energy tuning and the modification of topological surface states in TI. Recent studies on particle irradiation in TI have focused on precise local modifications in the TI system to induce magnetic topological ordering and surface selective topological superconductivity. Promising proposals for TI-integrated circuits have also been put forth. The eclectic range of irradiation-based studies on TI has been reviewed in this manuscript.