  Photonic quantum technologies such as effective quantum communication require
room temperature (RT) operating single- or few- photon sensors with high
external quantum efficiency (EQE) at 1550 nm wavelength. The leading class of
devices in this segment is avalanche photodetectors operating particularly in
the Geiger mode. Often the requirements for RT operation and for a high EQE are
in conflict, resulting in a compromised solution. We have developed a device
which employs a two-dimensional (2D) semiconductor material on a co-optimized
dielectric photonic crystal substrate to simultaneously decrease the dark
current by three orders of magnitude at RT and maintain an EQE of >99%. The
device is amenable to avalanching and form a basis for single photon detection
with ultra-low dark current and high photodetection efficiency. Harnessing the
high carrier mobility of 2D materials, the device has ~ps jitter time and can
be integrated into a large 2D array camera.
