Role of magnesium in band gap engineering of sub-monolayer type-II ZnTe quantum dots embedded in ZnSe

Abstract

Modification of the bandgap of sub-monolayer type-II ZnTe quantum dots (QDs), by means of direct incorporation of magnesium in the QDs, is reported. Nitrogen co-doped QDs embedded in a ZnSe matrix have been grown by a migration-enhanced molecular beam epitaxy technique. Incorporation of Mg in the ZnTe QDs decreases the valence band discontinuity, leading to reduced localization of the holes, which results in a higher electrical conductivity in the samples as deduced from the Hall effect measurements. The type-II alignment of the bands in the QDs is supported by intensity dependent and time-resolved photoluminescence measurements. Hall effect measurements indicate that the material has p-type conductivity with mid-1015 carriers/cm3 and hole mobilities in the 5–50 cm2/V·s range.