Detection wavelength tuning of InGaAs/GaAs quantum dot infrared photodetector with thermal treatment

Thermal treatment of In0.5Ga0.5As/GaAs quantum dot infrared photodetector (QDIP) structure has been carried out at 700 °C for 1 min with SiO2 capping layer. Thermal treatment of In0.5Ga0.5As/GaAs QDIP structure induced a blue-shift in its photoluminescence (PL) spectrum by a 50 meV with a reduction of its intensity. The blue-shift in PL spectrum and the reduction in PL intensity is thought to be due to the interdiffusion of In and Ga at the interfaces of quantum dots (QDs) and GaAs barriers. The fabricated QDIP with thermally treated structure showed a red-shift in its photocurrent spectrum by a 22 meV from the photocurrent peak of 200 meV for as-grown QDIP, as a consequence of the blue-shift of QD bandgap.