Cai Duanjun, Kang Junyong
Department of Physics and Semiconductor Photonics Research Center, Xiamen University, Xiamen 361005, China.
J Phys Chem B. 2006 Jun 1;110(21):10396-400. doi: 10.1021/jp0573801.
We report our investigation of phase transition of AlxGa1-xN thin films on GaN made by employing first-principles calculations. A critical thickness of two AlGaN molecular layers is determined for the wurtzite-to-zinc blende structural transition under compressive strains, which is associated with the second-nearest-neighbor interaction of electron bonds. Higher AlN mole fractions are found to favor the phase transition because of strong push toward covalency of the Al-N bonds under strains. Electronic structure results show that, after the phase transition, the spontaneous and piezoelectric polarizations of the AlGaN films are significantly reduced.
我们报告了通过第一性原理计算对在GaN上生长的AlxGa1-xN薄膜的相变进行的研究。确定了在压缩应变下纤锌矿结构向闪锌矿结构转变时两个AlGaN分子层的临界厚度，这与电子键的次近邻相互作用有关。发现较高的AlN摩尔分数有利于相变，因为在应变下Al-N键的共价性有强烈的增强趋势。电子结构结果表明，相变后，AlGaN薄膜的自发极化和压电极化显著降低。
