High‐Speed Photoresponse of CVD‐Grown Lateral TMD Heterostructures

ABSTRACT Although chemical vapor deposition (CVD) enables wafer‐scale fabrication of transition metal dichalcogenide (TMD) photodetectors, CVD‐grown devices are often limited by high defect densities and are generally considered significantly slower than devices based on exfoliated materials. Here, we demonstrate that the extrinsic response time of CVD‐grown TMD photodetectors can be substantially reduced by built‐in electric fields arising from p‐n junctions but also asymmetric Schottky barriers in monolayer lateral heterostructures. In particular, the heterostructure devices exhibit response times improved by 1.5‐2 orders of magnitude compared to devices based on a single TMD material. With that, our fastest devices achieve bandwidths exceeding 230 MHz, corresponding to fall times on the order of 1 ns.