Exploration of epitaxial quantum dots within wide band gap metamorphic host materials for intermediate band solar cells

The use of metamorphic (lattice-mismatched) host materials for the growth of Stranski-Krastanov type epitaxial quantum dots (QDs) is explored. Two alloys that provide access to wide band gaps (up to and above 2.0 eV), GaAsP and InGaP, are considered and compared to their lattice-matched analogs. InGaAs/GaAsP QD/host structures are found to yield smaller and denser QDs, with a stronger photoluminescence (PL) blue-shift, than the equally-strained lattice-matched InGaAs/GaAs system. Metamorphic InP/InGaP QDs are found to appear nearly identical to the lattice-matched analogs, but do exhibit a slightly larger PL blue-shift. Results indicate the potential for using metamorphic substrates to provide additional tailoring of QD properties, in addition to providing access to QD/host materials combinations that are more consistent with intermediate band solar cell design requirements.