磁场对GaAs/Al_xGa_(1-x)As异质结系统中束缚极化子的影响  

Influence of Magnetic Field on Bound Polarons in Semiconductor GaAs/Al_xGa_(1-x)As Heterojunctions

作　　者：张敏[1] 班士良[1] 

机构地区：[1]内蒙古大学理工学院物理系,呼和浩特010021

出　　处：《Journal of Semiconductors》2004年第12期1618-1623,共6页半导体学报（英文版）

基　　金：国家自然科学基金资助项目 (批准号 :60 1660 0 2 )~~

摘　　要：对 Ga As/ Alx Ga1 - x As单异质结系统引入三角势近似异质结势 ,同时考虑体纵光学 (L O)声子和有效近似下两支界面光学 (IO)声子的影响 ,采用变分法讨论了外界恒定磁场对束缚于近界面杂质的光学极化子结合能的影响 .利用改进的 L ee- L ow- Pines(L L P)中间耦合方法处理电子 -声子和杂质 -声子的相互作用 ,计算了杂质态结合能随杂质位置、磁场强度、电子面密度的变化关系 .结果表明 ,极化子结合能随磁场呈现增加的趋势 ,其中 L O声子对结合能的负贡献受磁场影响显著 ,而 IO声子的负贡献受磁场的影响并不明显 ,但当杂质靠近界面时 ,杂质 - IO声子相互作用对磁场的影响很敏感 .结果还表明 ,导带弯曲作用不容忽略 ;电子像势对结合能的影响很小 ,可以忽略 .A modified LLP variational method is adopted to investigate the binding energies of bound polarons near the interface of single heterojunction system of semiconductor in the presence of static uniform magnetic field by using a triangular potential approximate to the interface potential.The influences of the electron-phonon and impurity-phonon interaction including the effect of half-space bulk longitudinal and interface-optical phonon modes are considered.The computation is performed for GaAs/Al xGa 1-xAs structure.The relations among the impurity binding energies and the impurity position,magnetic field strength,the electron areal density are calculated,respectively.It is found that binding energy of the bound polaron shows a monotonic increase tendency with increasing the magnetic field strength B.The contribution from bulk longitudinal optical phonons to the binding energy obviously increases with increasing B,but the interface optical phonons are insensitive to magnetic field except for the impurity being near the interface.It also shows that the conductive band bending can not be neglected.Furthermore,the influence of the electron image potential is negligibly small so that it can be neglected in the further discussion.

关 键 词：GAAS/ALXGA1-XAS 异质结 磁场 束缚极化子 结合能 

分 类 号：O471.3[理学—半导体物理]