Electric field effect on the donor impurity states in zinc-blende symmetric InGaN/GaN coupled quantum dots

Based on the effective-mass approximation, the donor binding energy in a cylindrical zinc-blende (ZB) symmetric InGaN/GaN coupled quantum dots (QDs) is investigated variationally in the presence of an applied electric field. Numerical results show that the ground-state donor binding energy is highly dependent on the impurity positions, coupled QDs structure parameters and applied electric field. The applied electric field induces an asymmetric distribution of the donor binding energy with respect to the center of the coupled QDs. When the impurity is located at the center of the right dot, the donor binding energy has a maximum value with increasing the dot height. Moreover, the donor binding energy is the largest and insensitive to the large applied electric field (F?400 kV/cm) when the impurity is located at the center of the right dot in ZB symmetric In_0.1Ga_0.9N/GaN coupled QDs. In addition, if the impurity is located inside the right dot, the donor binding energy is insensitive to large middle barrier width (Lmb?2.5 nm) of ZB symmetric In_0.1Ga_0.9N/GaN coupled QDs.     

Hydrogenic impurity states in zinc-blende InxGa1−xN/GaN in cylindrical quantum well wires

Within the framework of effective-mass approximation, the binding energy of a hydrogenic donor impurity in zinc-blende (ZB) In_xGa_1−x  N/GaN cylindrical quantum well wires (CQWWs) is investigated using variational procedures. Numerical results show that the ground-state donor binding energy _Eb$E_b$ is highly dependent on the impurity position and the CQWWs structure parameters. The donor binding energy for a shallow donor impurity located at the center of the CQWWs is the largest. As the impurity position changes from the center of the wire to its edge, the donor binding energy gets smaller. Also, we have found that In concentration is a very important value to tailor the system, since the binding energies close to binding energy maxima are strongly dependent on In content.