Quantum dot infrared photodetectors

Self-assembled strained semiconductor nanostructures have been grown on GaA s substrates to fabricate quantum dot infrared photodetectors. State-fillin g photoluminescence experiments have been used to probe the zero-dimensiona l states and revealed four atomic-like shells (s,p,d,f) with an excitonic i ntersublevel energy spacing which was adjusted to similar to 60 meV. The lo wer electronic shells were populated with carriers by n doping the heterost ructure, and transitions from the occupied quantum dot states to the wettin g layer or to the continuum states resulted in infrared photodetection. We demonstrate broadband normal-incidence detection with a responsivity of a f ew hundred mA/W at a detection wavelength of similar to5 mum. (C) 2001 Amer ican Institute of Physics.