Characterization of In0.5Ga0.5As quantum dot infrared photodetector (QDIP) structures treated with post-growth processes

We report the modification of the characteristics of quantum dot infrared photodetectors (QDIPs) by thermal treatment and hydrogen plasma (H-plasma) treatment. H-plasma treatment on the QDIP induced structural change in 3-stacked In0.5Ga0.5As quantum dots (QDs) active region, resulting in bi-modal type two photoluminescence peaks. H-plasma treated QDIP showed a blue-shift of photocurrent spectrum by 110 meV with an increase of operation temperature from 50 to 130 K, which is attributed to relatively thermally stable intersubband transition from larger QDs. Thermal treatment of QDIP structure at 700 °C for 1 min with SiO2 capping layer induced intermixing of In and Ga atoms in QDs, resulting in a blue-shift of PL spectrum by 48 meV. Thermally treated QDIP showed a red-shift of photocurrent spectrum by 22 meV as a result of bandgap change with intermixing.