Ultrahigh-gain colloidal quantum dot infrared avalanche photodetectors.

Colloidal quantum dots (CQDs) are promising for infrared photodetectors with high detectivity and low-cost production. Although CQDs enable photoinduced charge multiplication, thermal noise in low-bandgap materials limits their performance in IR detectors. Here we present a pioneering architecture of a CQD-based infrared photodetector that uses kinetically pumped avalanche multiplication. By applying a strong electric field to a thick CQD layer (>540 nm), electrons acquire kinetic energy beyond the bandgap of the CQD material, initiating kinetically pumped charge multiplication. Optimizing the dot-to-dot distance to approximately 4.1 nm improves performance by balancing impact ionization and electron hopping. Our optimized CQD-based infrared photodetector achieved a maximum multiplication gain of 85 and a peak detectivity of 1.4 × 10 Jones at 940 nm. This architecture offers potential for single-photon detection and ultrahigh detectivity applications.