Colloidal Quantum Dot Enhanced Short-Wavelength Infrared Absorption of Avalanche Photodetectors

Avalanche Photodetectors (APDs) are characterized by high gain, fast response, and high sensitivity while operating under a certain bias voltage. Unfortunately, due to the limitations of the silicon material, silicon-based APDs are not sensitive enough to detect wavelengths beyond 1100 nm, which restricts their applications in various fields. One possible solution to detect short-wave infrared (SWIR) light is coating colloidal quantum dots (CQDs) with a tunable energy bandgap on the silicon surface of APD. In this study, an APD using colloidal lead sulfide (PbS) quantum dot material with engineered energy bands is designed, enhancing the short-wavelength infrared sensing capabilities. Through TCAD simulation, the detector is demonstrated to have a responsivity of 8.1 A/W, a quantum efficiency (QE) of 647%, a rise time of 0.52 ns, and a fall time of 3 ns at 1550 nm. The optimized device structure and doping configuration are of benefit to a high signal-to-noise ratio (SNR). Furthermore, the compatibility of this approach with CMOS technology and the low-cost colloidal quantum dots synthesis significantly reduces the costs of real-time applications in short-wavelength infrared range.