高Al含量AlGaN多层外延材料的应变与位错密度研究

文中利用X射线三轴衍射测试手段对高Al ( x≥0. 45)含量p2i2n结构的Alx Ga1 - xN外延材料进行测试,并结合倒易空间图(RSM)和PV函数法对Alx Ga1 - xN外延材料进行评价。首先通过对RSM的定性分析,给出多层外延材料中不同Al组分Alx Ga1 - xN材料的应变状态和位错密度等信息,然后结合PV函数法拟合了从RSM中分离出的摇摆曲线,通过拟合过程准确地计算了多层结构中不同组分的Alx Ga1 - xN材料的纵向和横向应变量与螺位错密度,测试及计算结果都表明:多层p2i2n结构的Alx Ga1 - xN外延材料的应变与位错密度与单层结构相差较大,表明层与层之间的应变和位错相互作用对各层的应变的位错密度有重要的影响。

Research of Strain State and Dislocation Density in the Multiple AlGaN Epitaxial Layers with High Al Content

The p-i-n multip le-layerAlxGa1 - xN samp le with high Al ( x > 0. 45 ) contentwasmeasured by the trip le-axis X-ray diffraction method. The RSM ( recip rocal space map) method and PV function were first combined to give more detailed information about the ep itaxial AlxGa1 - xN materials. The strain state and screw dislocation density of each layer of AlxGa1 - xN ep itaxialmaterialwere determined by RSM method. Then, the PV function was used to fit the rock curves separated from the RSM. At last, the strain and the screw dislocation density of each layerwas accu-rately calculated. The calculated results show that the strain-state and the screw density of AlxGa1 - xN multip le-lay-ered structure are so differentwith those of single-layer structure AlxGa1 - xN.The differences indicated that the inter-action of the strain and the dislocation can affect those in each layer, consequently.