导带弯曲对有限深GaN/Ga_(1-x)Al_xN球形量子点中杂质态的影响及其压力效应(英文)

Effect of Band Bending on the Impurity State in a GaN/Ga_(1-x)Al_xN Spherical Finite-potential Quantum Dot under Pressure

用三角势近似界面导带弯曲,采用变分理论研究了流体静压力影响下有限高势垒GaN/Ga1-xAlxN球形量子点中杂质态的结合能,计算中考虑了电子有效质量,电子面密度,介电常数以及禁带宽度随流体静压力的变化.数值计算结果表明,随着电子面密度的增加,杂质态结合能降低,当电子面密度较大时,随着量子点尺寸的增大,结合能最终趋于一个相同的值.同时发现随着压力的增加,在0到10GPa范围内,施主杂质态的结合能随压力变化呈线性增加的趋势,此变化趋势对于小量子点更显著.另外,随着铝组分的增加结合能相应的增加,此变化趋势对于铝组分低的情况更显著.结果表明导带弯曲效应对结合能的贡献是不能忽略的.

A variational approach is used to investigate the binding energy of the impurity state in a GaN/Gal-xAlxN spherical finite-potential quantum dot by using a triangular potential to approximate the band bending of the interface potential. Variations of electronic effective mass, electron areal density, dielectric constants and energy gap with hydrostatic pressure are considered. The numerical results show that the binding energies of impurity states decrease with the electron areal density increase, when the electron areal density is larger the binding energy tends to the same value as the quantum dot radius increases. It is also found that the binding energy linearly increases with the pressure from 0 to 10 GPa,and the influence of hydrostatic pressure is larger for a smaller quantum dot. It is seen clearly that the donor binding energies increase as the increase of A1 concentration, especially for the low A1 concentration. Furthermore, it indicates that the conductive band bending can not be neglected.