Enhanced negative terahertz photoconductivity enabled by interfacial charge transfer in Te/graphene mixed-dimensional heterojunction

Negative terahertz photoconductivity is a rare effect that holds great significance for numerous applications. However, the maintenance and enhancement of negative photoconductivity response still face a huge challenge. Here, combined with material selection and band alignment engineering, we have proposed a mixed-dimensional heterostructure comprised of 1D tellurium (Te) nanowires and 2D monolayer graphene. Intriguingly, the Te/graphene heterojunction could enhance negative terahertz photoconductivity by twice compared with graphene, following a transition from negative to positive photoconductivities. We have further performed first-principles calculations and characterizations to elucidate the type-I band alignment at the heterointerface, revealing the phenomena attributed to interfacial charge transfer. Our results provide in-depth physical insights into the carrier transport mechanism, which is crucial for further exploration of optoelectronic devices based on mixed-dimensional heterostructures.