The influence of doping on the device characteristics of In0.5Ga0.5As/GaAs/Al0.2Ga0.8As quantum dots-in-a-well infrared photodetectors

Abstract

We report on a detailed analysis of the effects of doping on the main device parameters of In_0.5Ga_0.5As/GaAs/Al_0.2Ga_0.8As quantum dots-in-a-well infrared photodetectors. Due to the relatively large conduction band offset of GaAs/Al_0.2Ga_0.8As (167meV) transitions from wetting layer to quantum well states are observed for the highly doped devices. Since increasing the doping concentration fills the quantum dot states, electrons are forced to occupy the one-dimensional wetting layer states and therefore have quantum-well-like properties. This has facilitated a comparative study of the effects of three-dimensional and one-dimensional confinement of electrons on device parameters such as the responsivity and dark current by studying one particular detector structure with different doping concentrations of the active region.