GaN/AlN半导体异质结带阶超原胞法计算

Super Cell Calculation of GaN/AlN Semiconductor Heterojunction Valence-band Offsets

为了对GaN/AlN异质结电子结构有更为深入的认识,采用超原胞模型,对其进行了基于密度泛函理论的第一性原理计算.结果发现GaN/AlN为突变同型异质结,价带顶带阶为0.62eV,与实验值很接近.通过使用常用的平均键能法、平均势法和芯态法三种近似方法对GaN/AlN带阶的计算,比较得出,超原胞法虽然计算量较大,但能够给出异质结界面附近更为详细的信息,这一点其他三种近似方法无法得到,但他们也能够得出与实验值基本一致的带阶参量.

In order to have a more in-depth understanding of the electronic structure of GaN/AlN heterojunction, it was calculated by the density functional theory based on the first principle plane wave pseudopotential method, via the super cell model. The direct calculation of the GaN/AlN super cell demonstrated that the GaN/AlN heterojunction was homotype and changed abruptly at the interface. Besides, the valence-band offsets of GaN/AlN was 0.62 eV, which was very close to the experimental result. Additionally, it could be concluded that the super cell calculation had more advantages than the other common indirect calculation of heterojunction band offsets, such as the average bond energy, the average potential and the core state. The super cell calculation supplied more information of the GaN/AlN heterojunction interface while the reference energy band methods could not. Nevertheless, band-offsets parameters obtained by the other indirect methods were also reasonable compared with the experimental value.