The operation principle of the well in quantum dot stack infrared photodetector

Abstract

The well in the quantum dot stack infrared photodetector (WD-QDIP) is proposed which can be operated at high temperature ∼230 K. The operation principle of this device is investigated, including the carrier transport and the enhancement in the photocurrent. The WD-QDIPs with different well numbers are fabricated to study the mechanisms. It is realized that the carrier transport from the emitter to the collector in traditional quantum dot infrared photodetectors consists of two channels deduced from current-voltage characteristics and dark current activation energy at different temperatures. At temperatures below 77 K, the current transports through the InAs quantum dot channel, whereas at temperatures higher than 77 K, the current is dominated by the GaAs leakage channel. In addition, the non-equilibrium situation at low temperatures is also observed owing to the presence of photovoltaic phenomenon. The carrier distribution inside the QDs is simulated to investigate the reasons for the increase of photocurrent. Based on the simulation and the photocurrent response, the hot carrier (electron) scattering effect by the insertion of a quantum well layer is inferred as the most probable reason that lead to the enhancement of the response and regarded as the key factor to achieve high- temperature operation.