Shallow donor impurity states in wurtzite InGaN/GaN coupled quantum wells under built-in electric field, hydrostatic pressure, and strain effects

In this paper, we investigated theoretically the hydrogenic donor impurity states in strained wurtzite (In,Ga)N-GaN coupled quantum wells (CQWs). The variational approach is employed to obtain the dependence on built-in electric field (BEF), hydrostatic pressure, indium composition, and structure size of the binding energy of hydrogenic donor impurity (BEHDI). The results reveal that hydrostatic pressure and structure size of the CQWs have a great influence on BEF which affects strongly the BEHDI. With the increment in hydrostatic pressure, the BEF strength of well and barrier layers enhances monotonously. However, by increasing the well width (barrier width), the BEF strength of well layer reduces (enhances) gradually, and that of barrier layers enhances (reduces). Meantime, it reveals that the binding energy (1) enhances linearly as the hydrostatic pressure is increased, (2) is more sensitive to geometrical parameters (width of well and/or barrier), and (3) demonstrates a maximum value as an impurity ion is shifted from one side of the CQWs to the other.