Unveiling Electric Field Induced Ultrafast Charge Transfer Dynamics and Photoresponse Enhancement in Gold‐Interlayered Bi₂Se₃

Abstract

In the realm of optoelectronic applications, the incorporation of a metal interlayer between layers of a topological material holds significant potential. The interlayer introduces benefits such as improved charge transfer efficiency, tunable band alignment, plasmonics effect, and enhanced light‐matter interactions, paving the way for more efficient and versatile optoelectronic devices. This work explores the incorporation of gold between Bi2Se3, resulting in an enhancement in the response time of photoresponse of interlayered systems (Bi2Se3‐Au‐Bi2Se3). The introduction of a gold interlayer between Bi2Se3 significantly influences the overlayer structure, crystallinity, crystallite size, and even phonon behavior. Moreover, the responsivity of the interlayered device at a bias (2 V) is found to have high responsivity with fast response and decay time (τr = 0.1 ms, and τd = 24 ms of interlayered systems) as compared to intrinsic Bi2Se3(τr = 0.6 ms, and τd = 28 ms). This change is attributed to the bandgap alteration of the Bi2Se3/Au interface, which is monitored through transient spectroscopy performed at different electric biases. This study suggests that incorporating a gold interlayer holds potential benefits for various optoelectronic applications.

Unveiling Electric Bias Effects on Ultrafast Carrier Dynamics in Multiple Stacked ZnTe/Bi2Te3 Heterostructures

“…A detailed explanation is provided in the Supporting Information for a comprehensive understanding. Considering all of the possible transient spectra and kinetic profiles of 2- and 4-layered vdW HS at different excitations as well as at different external biases, it can be proposed that Fermi-level modulation and variation in the concentration of Dirac electrons influence the trap and defect states and, consequently, the carrier dynamics in these materials. − Thus, the trap and defect states in 4-layered vdW HS help uniformly distribute voltage-induced carriers that eventually reduce the heating effect as proposed in 2-layered vdW HS.…”