Energy level alignment of confined hole states in $InAs_1-x-ySb_xP_y$ double quantum dots

Abstract

We present a combined experimental and theoretical study of uncapped In(As,Sb,P) double quantum dots (DQD), suited for application in novel resonant tunneling nanodiods or single-photon nanooptical up- and down-converters in the mid-infrared spectral range. We provide details on the growth process using liquid-phase epitaxy (LPE), as well as on the characterization using atomic-force microscopy (AFM) and scanning electron microscopy (SEM). We find that most DQDs exhibit an asymmetry such that the two QDs of each pair have different dimensions, giving rise to correspondingly different quantum confinement of hole states localized in each QD. Based on these data, we have performed systematic simulations based on an eight-band $mathbfkcdotmathbfp$ model to identify the relationship between QD dimensions and the energy difference between corresponding confined hole states in the two QDs. Finally, we have determined the strength of an applied electric field required to energetically align the hole ground states of two QDs of different dimensions in order to facilitate hole tunneling.