Quantum-dot-based single-photon avalanche detector for mid-infrared applications

Abstract

A single-photon detector is presented with quantum dot (QD) layers in its absorption region. The proposed detector is a three-terminal device in which a QD-based absorption region is integrated with an avalanche multiplication region through a tunneling barrier and the applied bias of each region can be controlled separately. The mid-infrared single photons (λ=3∼5  μm) can be absorbed in QDs and the photogenerated electrons are drifted to the avalanche region to trigger an avalanche and generate an output pulse. Since the absorption region consists of doped QD layers, it is expected to have higher orders of dark count. However, by separately controlling the bias and keeping the electric field of absorption region low, the dark current of this region can be reduced. Our simulations predict a single-photon detection efficiency (SPQE) of about 0.7 at T=50  K for the proposed detector. At higher temperatures, the dark count rate increases and results in reduced SPQE. To increase the operation temperature, resonant tunneling barriers (RTB) are included in the absorption region to inhibit the thermally excited electrons from contributing to the dark current generation. Our results show that the SPQE for the RTB-based device is about 0.65 at T=77  K, which is approximately equivalent to the SPQE of the device without RTB at T=50  K.