Effects of doping on carrier confinement in InAs QD solar cells

The confinement depth of bound states in InAs quantum dots was studied as a function of QD doping. k·p simulation predicted a decrease of up to 50 meV in absolute confinement depth as QDs are doped due to local band bending from QD charging. Photoreflectance of solar cells containing QDs doped to several levels was used to determine optical transition energies, necessary to improve the fitting of Gaussian functions against temperature-dependent photoluminescence measurements. Arrhenius analysis was then used to extract activation energies for two QD bound states. Experimental results confirmed the simulated prediction, showing a decrease in activation energy of 40 meV for the QD ground state and 34 meV for the excited state.