Nanoscale avalanche photodiodes for highly sensitive and spatially resolved photon detection

The avalanche multiplication of the photocurrent in nanoscale p-n diodes consisting of crossed silicon-cadmium sulphide nanowires, is reported. Electrical transport and optical measurements demonstrated that the nanowire avalanche photodiodes (nanoAPDs) have ultrahigh sensitivity with detection limits less than 100 photons. The photon-detection limits of the nanoAPDs were determined using a calibrated laser excitation source, and also the temporal response of the nanoAPDs was investigated. The features demonstrated for the nanoAPDs in the study offers substantial promise in diverse areas ranging from nanopositioning, integrated photonics, and near-field detection to real-time observation of single protein dynamics.