Two-dimensional electron mobility limitation mechanisms in AlxGa1-xN/GaN heterostructures -: art. no. 045316
Two-dimensional electron mobility limitation mechanisms in AlxGa1-xN/GaN heterostructures -: art. no. 045316
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DOI：
10.1103/physrevb.72.045316
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发表时间：
2005-07-01
影响因子：
3.7
通讯作者：
Andersson, TG
中科院分区：
文献类型：
--
作者：
Gurusinghe, MN;Davidsson, SK;Andersson, TG
我们分析电子散射声子，电离杂质，线位错，和界面粗糙度在AlxGa 1-xN/GaN界面。这些机制是二维电子气中迁移率限制的原因。来自带电位错线、电离杂质和表面粗糙度的散射被添加到晶格散射过程中。位错线散射由一个新的二维电子散射解析模型描述。分析了总迁移率随温度（10-500 K）和电子浓度（0.05- 2 × 10（13）cm（-2））的变化。在10-300 K的温度范围内，计算结果与现有的和自己的实验数据进行了比较。在低于50 K的温度下，发现电离杂质散射和线位错散射限制迁移率。在室温及以上的温度下，光学声子散射占主导地位。对于AlGaN顶层和GaN沟道之间具有粗糙界面的样品，在高温和低温下都存在额外的粗糙散射。因此，为了在300 K或以上的高功率水平下工作的场效应晶体管中利用异质结构，必须仔细控制几个参数。对于二维电子气浓度为1 × 10（13）cm（-2）、室温下迁移率高于1500 cm（2）/V s的情况，电离杂质应小于1 × 10（17）cm（-3），线位错密度应小于1 × 10（10）cm（-2）。此外，表面粗糙度的均方根值需要小于1 nm，而横向表面粗糙度相关长度大于5 nm。
We analyze electron scattering from phonons, ionized impurities, line dislocations, and interface roughness at an AlxGa1-xN/GaN interface. These mechanisms are responsible for mobility limitations in a two-dimensional electron gas. Scattering from charged dislocation lines, ionized impurities, and surface roughness are added to the lattice scattering processes. The dislocation line scattering is described by a new analytical model for the two-dimensional electron scattering. The total mobility variations with temperature, 10-500 K, and electron concentration, 0.05-2x10(13) cm(-2), were analyzed. Calculations were compared with available and own experimental data in the temperature range 10-300 K. At temperatures below 50 K the ionized impurity scattering and line dislocation scattering were found to limit the mobility. For temperatures at and above room temperature the optical phonon scattering was predominant. For samples having a rough interface between the AlGaN top layer and the GaN channel there was additional roughness scattering at both high and low temperatures. Therefore, to utilize the heterostructures in field effect transistors, operating at high power levels at or above 300 K, several parameters must be carefully controlled. For a two-dimensional electron gas concentration of 1x10(13) cm(-2) with mobility above 1500 cm(2)/V s at room temperature, the ionized impurities should be less than 1x10(17) cm(-3) and the line dislocation density below 1x10(10) cm(-2). Further, the root-mean-square value of the surface roughness need to be less than 1 nm with the lateral surface roughness correlation length larger than 5 nm.