Shallow-donor impurity in zinc-blende InGaN/GaN asymmetric coupled quantum dots: Effect of electric field

Abstract

We have performed a theoretical calculation of the shallow-donor impurity states in cylindrical zinc-blende (ZB) InGaN/GaN asymmetric coupled quantum dots (QDs), considering the effect of the electric field applied to the left (opposite to the growth direction). Numerical results show that the donor binding energy in ZB InGaN/GaN asymmetric coupled QDs is highly dependent on the impurity positions, asymmetric coupled QD structure parameters, and the electric field. In the presence of the electric field, if the left dot height is increased from zero, the donor binding energy of the impurity localized inside the middle barrier layer has a maximum value; if the right dot is increased from zero, the donor binding energy of impurity localized inside the right dot has a maximum value. It is also found that for the impurity located at the center of the right dot, the donor binding energy is insensible to the electric field when the electric field is large; however, the critical electric field is smaller if the right dot is wide. In particular, numerical results show that if the right dot is wide, the asymmetric coupled QDs are much easier to be decoupled under the influence of the electric field.