应变纤锌矿GaN/AlxGa1-xN柱形量子点中类氢施主杂质态结合能的压力效应

考虑应变，在有效质量、有限高势垒近似下，变分研究了纤锌矿GaN/AlxGa1-xN柱形量子点中类氢施主杂质态结合能随流体静压力、杂质位置及量子点结构参数(量子点高度、半径、Al含量)的变化关系．结果表明，类氢施主杂质态结合能随流体静压力增大而增大，且在量子点尺寸较小时，流体静压力对杂质态结合能的影响更为显著．受流体静压力的影响，杂质态结合能随量子点高度、半径的增加而单调减少，且变化趋势加剧；随Al含量增加而增大的趋势变缓．无论是否施加流体静压力，随着类氢施主杂质从量子点左界面沿材料生长方向移至右界面，杂质态结合能在量子点的右半部分存在一极大值．流体静压力使得极大值点向量子点中心偏移．

Influence of Hydrostatic Pressure on Binding Energy of Hydrogenic Donor Impurity States in a Strain Wurtzite GaN/AlxGa1-xN Cylindrical Quantum Dot

Within the effective-mass and finite potential barrier approximation, the binding energy of a hydrogenic donor impurity state as functions of the hydrostatic pressure, impurity position and the structural parameters of quantum dot(QD)( height, radius and Al content) is investigated theoretically for a strained wurtzite GaN/AlxGa1-xN cylindrical QD via a variational procedure, including the strong built-in electric field effect and strain dependence of material parameters. Numerical results show that the binding energy nearly linearly increases with increasing the applied hydrostatic pressure, and the pressure has a remarkable influence on the donor binding energy for small QD. Because of the effect of the applied hydrostatic pressure the donor binding energies decrease monotonously and then sensitive to the QD height and QD radius. Whereas, the donor binding energies increase lowly and then insensitive to the increase of Al content as increasing hydrostatic pressure. The binding energy of a hydrogenic donor impurity state has a maximum value with moving the impurity position from the left interface of QD to the right interface along the growth direction, and the position of the maximum value is located at the right side of the QD whether the hydrostatic pressure is considered or not. And the maximum is shifted toward the centre of QD as a result of the applied hydrostatic pressure.