AlGaN/GaN HEMT 2DEG电致耦合模型的研究

传统计算AlGaN/GaN异质结二维电子气(2DEG)的方法是根据Hooke定律计算c轴方向压应变与拉应变,然后利用压电模量计算出不依赖于栅压的2DEG,称为非耦合模型计算.提出了一种电致耦合模型来计算2DEG,在计算过程中考虑到弛豫度与附加电场对材料压电效应的影响,结果发现,当Al组分x=0.30时,压电极化电荷密度低于传统方法的计算值,两种模型的计算值相差7.17%,由此可见,当电场作用于材料时,材料产生逆压电效应,最终导致压电极化电荷密度降低.

Electromechanical Coupled Model on 2DEG in AlGaN/GaN HEMT

The standard theoretical investigation of 2DEG performed on AlGaN/GaN heterostructures is computing the c-plane stresses and strains based on the tensor formulation of Hooke's law, and then utilizing the piezoelectric moduli to calculate the constant net polarization charge which is independent of the 2DEG density. Electromechanical coupled model concerning crystal relaxation was introduced, which relates stress to the added electric field and to the strain in AlGaN/GaN heterostructure. It is found that the polarization charge computed by electromechanical coupled model is 7.17% less than that obtained by the standard theoretical method with Al mole fraction of 0.30. It is clear that when the electric field is applied on the material of AlGaN/GaN heterostructure, the inverse piezoelectric polarization occurs, which leads to the reduction of polarization charge density finally.