ZnMgO/ZnO 异质结构中二维电子气的研究*

摘要

Based on the band structure and related theoretical model of two-dimensional electron gas (2DEG), the dependence of the distri-bution of 2DEG on the thickness of ZnMgO barrier and related Mg content in ZnMgO/ZnO heterostructures has been computed by self-consistently solving the coupled Schrodinger and Poisson equations. Computation results reveal a critical thickness of the ZnMgO barrier for 2DEG formation, with no 2DEG occurring as the barrier thickness is below the critical value. When the thickness is above the value, the density of the 2DEG increases linearly with the thickness of ZnMgO barrier and saturates finally. The density of the 2DEG also shows a strong dependence on the Mg content in the ZnMgO barrier, with an obvious increase obtained as the Mg content enhances. At the same time, we compare the computed results with experimental data reported in the references with a certain degree of consistence obtained. Explanations and discussions of the above comparison have been presented in the study from the views of polarization effects and band structure.%　　论文根据 ZnMgO/ZnO 异质结构二维电子气的能带结构及相关理论模型，采用一维 Poisson-Schrodinger 方程的自洽求解，模拟计算了 ZnMgO/ZnO 异质结构中二维电子气的分布及其对 ZnMgO 势垒层厚度及 Mg 组分的依赖关系。研究发现该异质结构中 ZnMgO 势垒层厚度存在一最小临界值：当垒层厚度小于该临界值时，二维电子气消失，当垒层厚度大于该临界值时，其二维电子气密度随着该垒层厚度的增加而增大；同时研究发现 ZnMgO 势垒层中 Mg组分的增加将显著增强其二维电子气的行为，导致二维电子气密度的明显增大；论文对模拟计算获得的结果与相关文献报道的实验结果进行了比较，并从极化效应和能带结构的角度进行了分析和讨论，给出了合理的解释。