【摘要】 从Ⅲ族氮化物中压电极化对应变弛豫度的依赖关系出发 ,通过自洽求解薛定谔方程和泊松方程 ,分别研究了自发极化、压电极化和AlGaN势垒层掺杂对AlxGa1 -xN GaN异质结构二维电子气的浓度、分布、面密度以及子带分布等性质的影响 .结果表明 :二维电子气性质强烈依赖于极化效应 ,不考虑AlGaN势垒层掺杂 ,当Al组分为 0 3时 ,由极化导致的二维电子气浓度达 1 6× 10 1 3cm- 2 ,其中压电极化对二维电子气贡献为 0 7× 10 1 3cm- 2 ,略小于自发极化的贡献 (0 9× 10 1 3cm- 2 ) ,但为同一数量级 ,因而通过控制AlGaN层应变而改变极化对于提高二维电子气浓度至关重要 .AlGaN势垒层掺杂对二维电子气的影响较弱 ,当掺杂浓度从 1× 10 1 7增加到 1× 10 1 8cm- 3时 ,二维电子气面密度增加 0 2× 10 1 3cm- 2 .更多还原

【Abstract】 The two-dimensional electron-gas (2DEG) distribution, sheet density and subband occupations in Al xGa 1-xN/GaN heterostructure are calculated by solving the coupled Schrdinger and Poisson equations self-consistently. By involving degree of relaxation to distinguish the spontaneous and piezoelectric polarizations, the influence of the polarizations and the doping in the AlGaN barrier on the 2DEG properties are investigated separately. It is found that the 2DEG properties depend much stronger on the polarizations than on the doping, and that the contribution of the spontaneous polarization is dominant. The 2DEG sheet density is calculated to be 1.6×10 13cm -2 with an Al-content of x=0.3 in the strained AlGaN barrier, the contributions of spontaneous and piezoelectric polarizations are 0.9×10 13 and 0.7×10 13cm -2 respectively. When the doping of the AlGaN barrier is increased from 1×10 17 to 1×10 18cm -3, the 2DEG sheet density is increased by 0.2×10 13cm -2.更多还原