化学有序Al_xGa_(1-x)N合金的第一性原理研究(英文)

First-Principle Study of Chemically Ordered Al_xGa_(1-x)N Alloys

基于第一性原理方法系统研究了化学有序结构AlxGa1-xN合金的结构特征和电子性质.结果表明:随着组分x的增大,化学有序结构AlxGa1-xN合金的晶格常数逐渐减小,而结构稳定性变强.计算的电子结构揭示:化学有序结构AlxGa1-xN合金是直接带隙半导体,其带隙随着x的增大而变宽.化学有序化对带隙变化的影响可能源于量子阱的局域化,且化学有序结构AlxGa1-xN的化学键是包含明显离子特性的共价键.

First-principles calculations have been carried out to study the chemically ordered AlxGa1-xN（0〈x 〈 1 ） alloys. The results showed that with the increase of x { 0 〈 x 〈 1 }, the lattice parameter of chemically or- dered AlxGa1-xN alloys was decreased, and the stability was enhanced from energetic point of view. The calculat- ed electronic structure demonstrated that the chemically ordered AlxGa1-xN（0 〈x 〈 1 ） alloys were still direct-gap semiconductors, and the band-gap of chemically ordered AlxGa1-xN alloys were increased with increasing x （0 〈 x 〈 1 ）. The effects of ordering on band gap may be due to localization of quantum-well-like states, and the bond of chemically ordered AlxGa1-xN alloys is covalent bond with strong ionic characteristics.