光学声子散射对纤锌矿AlN/GaN异质结中电子迁移率的影响

Influence of Optical-phonon Scattering on Electron Mobility in a Wurtzite AlN/GaN Heterostructure

考虑导带弯曲和有限高势垒,利用变分法和力平衡方程研究了界面光学声子和半空间光学声子散射对纤锌矿AlN/GaN异质结中二维电子气(2DEG)迁移率的影响,数值计算了各支光学声子作用下迁移率随电子面密度及温度的变化.结果表明:总迁移率随电子面密度先上升后下降,随温度升高则一直呈下降趋势.在较低电子面密度时,沟道区的体纵光学声子散射为影响迁移率的主要因素;当电子面密度大于4×1013/cm2时,界面声子散射成为主要因素.

A variational method and the force balance equation are adopted to investigate the influence of optical-phonon scattering （including interface optical phonons and half-space optical phonons） on the mobility of a two-dimensional electron gas in a wurtzite AlN/GaN heterostructure by taking energy band bending and finite barrier into account. The electron mobilities influenced by each branch of optical-phonon modes are plotted as functions of areal electron density and temperature. The results show that the total mobility increases firstly, and then decreases significantly as the electronic density increases, while it always decreases with increasing temperature. It is also shown that the scattering from half-space optical-phonons in the channel dominates the contribution to the mobility at low electronic density, whereas the scattering from interface phonons plays a more important role when the electronic density is larger than 4 × 10^13/cm^2.