界面效应对GaN/Ga1-xAlxN量子点中杂质态的影响

在有效质量近似下采用变分法以及界面处导带弯曲用三角势近似,研究了氮化物半导体GaN/Ga1-xAlxN材料中杂质态的结合能随量子点尺寸及电子面密度的变化关系.结果表明,导带弯曲对结合能的影响不容忽视.当电子面密度较大时候,随着量子点尺寸的增大,杂质态结合能随电子面密度的增大呈线性变化,而在电子面密度较大时,结合能随着量子点半径的增加而迅速减小,且在某个尺寸附近出现极小值,然后缓慢增大.与其不同的是,对Zn1-xCdxSe/ZnSe结构,结合能则随着量子点半径的增加呈现非线性单调减小.

Interface Effect on the Impurity State in a GaN/Ga1-xAlxN Quantum Dot

A modified variational method within the effective-mass approximation is adopted to investigate the impurity state binding energies of a GaN/Ga1-xAlxN quantum dot heterojunction system by using a triangular potential to approximate the interface potential. The ground state binding energies are calculated as functions of the quantum dot radius and the electron areal density. It is shown that the influence of conductive band bending should not be neglected. As the electron areal density is bigger,the binding energies are not monotonic decrease with increasing the quantum dot radius R. It should be also pointed out that the binding energy linearly increases with the electron areal density. The computation also has been performed for the Zn1-xCdxSe/ZnSe structure,but the conclusion is different with that of a nitride semiconductor quantum dot.