Hot carrier transfer in Bi2Se3/Te heterostructure promoted by substrate-introduced effective field

Abstract

Van der Waals heterostructures with negligible lattice mismatch and flexible fabrication provide a platform to modulate the photoactive properties and extend the applications of two-dimensional materials. In addition to the band alignment, the substrate-introduced effective electric field is also indispensable for manipulating the carrier dynamics at the heterointerface. Here, we have proposed a heterostructure composed of tellurium (Te) and bismuth selenide (Bi2Se3) nanofilms to regulate the influence of the substrate field via the stacking order. Our experimental results demonstrate that the terahertz transient photoresponses of the two types of heterojunctions exhibit distinct modulation depths and carrier lifetimes. Notably, unlike the Te/Bi2Se3 configuration, where the Bi2Se3 interlayer serves as a spacer to screen the substrate field, the Bi2Se3/Te heterostructure possesses faster relaxation due to hot carrier transfer promoted by the substrate-introduced effective field. This work provides in-depth physical insights into substrate engineering, which is crucial for further exploration of terahertz optoelectronic devices.