Photoelectric properties of the metamorphic InAs/InGaAs quantum dot structure at room temperature

We present the study of optical and photoelectric properties of InAs quantum dots (QDs) grown on a metamorphic In0.15Ga0.85As buffer layer: such nanostructures show efficient light emission in the telecom window at 1.3 μm (0.95 eV) at room temperature. We prepared a sample with vertical geometry of contacts isolated from the GaAs substrate. The structure is found to be photosensitive in the spectral range above 0.9 eV at room temperature, showing distinctive features in the photovoltage and photocurrent spectra attributed to QDs, InAs wetting layer, and In0.15Ga0.85As metamorphic buffer, while a drop in the photoelectric signal above 1.36 eV is related to the GaAs layer. No effect of defect centers on the photoelectrical properties is found, although they are observed in the absorption spectrum. We conclude that metamorphic QDs have a low amount of interface-related defects close to the optically active region and charge carriers can be effectively collected into InAs QDs.