Fast photodetectors that convert an on-chip optical signal into an electrical output at high-speed are vital for modern imaging, sensing, and communication systems . Operation at telecom wavelengths is especially preferred due to low transmission losses and the availability of optical gain. Two-dimensional (2D) transition metal dichalcogenides (TMDCs) with bond-free van der Waals (vdW) structures possess relatively large carrier mobilities and intrinsic response times on the order of picoseconds , demonstrating great potential for the next generation of ultrafast photodetectors.