Optical and electrical properties of stacked binary InAs-GaAs quantum dot structures prepared under surfactant-mediated growth conditions

The structural, optical and electrical properties of a 10-layer InAs/GaAs quantum dots (QDs) system having InAs layers (2.9ML) grown under surfactant growth conditions, using only an impinging In beam, were investigated. This growth mode still resulted in the formation of quantum dots, but with dot sizes smaller and sample quality better than those for normal growth (NG) of ~3ML InAs-GaAs QD structures. Room temperature photoluminescence measurements showed PL emission from this sample at 1200-1300 nm, i.e. reaching the telecom O-band. At low substrate growth temperatures (LT), 250oC, and under the same “Arsenic free” growth condition an InAs/GaAs superlattice structure without the formation of QD was successfully grown with up to 2.9MLs of InAs, which was not achievable under NG conditions. Both samples showed a noticeable photocurrent when illuminated with 1.2 - 1.3 µm lasers. Thus they can be used as photoconductive materials that can be excited at the telecom wavelengths of 1.3 µm for Terahertz or other optoelectronic applications.