三元混晶双势垒结构中光学声子辅助共振隧穿及压力效应

Optical phonon-assisted resonant tunneling in double-barrier structures consisting of ternary mixed crystals and its pressure effect

采用连续介电模型,细致探讨了AlxGa1-xAs/GaAs双势垒结构中界面声子的色散关系及其与电子的耦合作用.进而采用Fermi黄金法则,在该结构的垒或阱为三元混晶材料时,分别计算了声子辅助隧穿电流密度.结果表明,在宽阱情形下,若垒为混晶材料,混晶效应不明显,只有一个明显的声子峰,该结论与实验符合较好;若阱为混晶材料,则混晶效应明显,具有两个声子峰,该结论对实验有指导意义.本文还讨论了压力对声子辅助共振隧穿的影响,结果显示:声子辅助隧穿峰和共振峰的峰值均随压力增加而减小,但声子辅助隧穿效应则随压力增加.

The optical phononassisted resonant tunneling in AlxGal-xAs/GaAs double barrier structures consisting of ternary mixed crystals has been discussed theoretically. Within the framework of the dielectric continuum model, the dispersion relation of interface optical phonon modes and the interaction between an electron and interface optical phonons in these structures are investigated. Furthermore, the optical phononassisted tunneling is discussed using the Fermi golden rule and the phononassisted tunneling current is calculated for the barriers and wells being ternary mixed crystals, respectively. It is found that only one phonon-assisted tunneling peak appears for ternary mixed crystals as barriers. This conclusion agrees well with that given by experiments. Whereas, the effect of ternary mixed crystal is obvious, that two phononassisted tunneling peaks appear for ternary mixed crystals as wells. This may give a guidance to further experiments. The effect of pressure on tunneling current has been also discussed. The result shows that the phononassisted tunneling peaks and the resonant tunneling peak are reduced with the pressure increasing. The effect of phononassisted tunneling is increased with the pressure.