Heterostructures of wurtzite based devices have attracted great research interests since the tremendous success of GaN in light emitting diodes (LED) industry. Among the possible heterostructure material candidates, high quality GaN thin films on inexpensive and lattice matched ZnO substrate are both commercially and technologically desirable. However, the energy of ZnO polar surfaces is much lower than that of GaN polar surfaces. Therefore, the intrinsic wetting condition forbids such heterostructures. As a result, poor crystal quality and 3D growth mode were obtained. To dramatically change the growth mode of the heterostructure, we propose to use hydrogen as a surfactant, confirmed by our first principles calculations. Stable H involved surface configurations and interfaces are investigated, with the help of newly developed algorithms. By applying the experimental Gibbs free energy of H$_2$, we also predict the temperature and chemical potential of H, which is critical in experimental realizations of our strategy. This novel approach will for the first time make the growth of high quality GaN thin films on ZnO substrates possible. We believe that our new strategy may reduce the manufactory cost and improve the crystal quality and the efficiency of GaN based devices.
Tunable electronic properties and band alignments of MoSi$_2$N$_4$/GaN and MoSi$_2$N$_4$/ZnO van der Waals heterostructures
范德华异质结构（VDWH）是一种新兴的策略，工程的二维（2D）材料系统的电子性能。最近发现的MoSi $_2$ N $_4$-一个合成的七层的二维半导体具有特殊的机械和电子性能的启发，我们调查的协同作用\ce{MoSi2N4}与宽带隙（WBG）的GaN和ZnO的二维单层使用第一性原理计算。发现MoSi $_2$ N $_4$/GaN是直接带隙的I型VDHH，而MoSi $_2$ N $_4$/ZnO是间接带隙的II型VDHH.有趣的是，通过沿面外方向施加电场或机械应变，MoSi $_2$ N $_4$/GaN和MoSi $_2$ N $_4$/ZnO的能带结构可以被显著地改变，表现出丰富的过渡行为，例如I型到II型能带对准和直接到间接带隙转变。这些发现揭示了MoSi $_2$ N $_4$基WBG VDWH作为超紧凑光电应用中具有巨大设计灵活性的可调谐混合材料的潜力。
Mn as surfactant for the self-assembling of Al$_x$Ga$_{1-x}$N/GaN layered heterostructures
GAN和Al $_x$ Ga $_{1-x}$ N/GAN异质结构在Mn存在下通过金属有机气相外延生长的结构分析揭示了Mn如何影响生长过程，特别是Al的掺入、表面的形态以及GAN上的Al $_x$ Ga $_{1-x}$ N的塑性弛豫。此外，Mn的掺杂促进了层状Al $_x$ Ga $_{1-x}$ N/GAN超晶格异质结构的形成，为控制晶体生长过程中三元合金的偏析和促进功能层状结构的自组装开辟了广阔的前景。
Full optimization of quasiharmonic free energy with anharmonic lattice model: Application to thermal expansion and pyroelectricity of wurtzite GaN and ZnO
Thermal boundary conductance across epitaxial ZnO/GaN interfaces: Assessment of phonon gas models and atomistic Green's function approaches for predicting interfacial phonon transport
我们目前的实验测量的热边界电导（TBC）从$77 - 500$ K跨隔离异质外延生长的ZnO薄膜在GAN衬底上。这些数据提供了一个评估的假设，驱动声子气体模型为基础的扩散失配模型（DMM）和原子格林函数（AGF）预测TBC的形式主义。我们的测量结果，与以前的实验数据相比，表明TBC可以受到长波长，区域中心模式的界面一侧的材料，而不是在DMM假设的“振动失配”的概念，这种分歧是在高温下明显。在室温下，我们测量ZnO/GAN TBC为$490\lbrack +150, -110\rbrack$ MW m $^{-2}$ K $^{-1}$。DMM和AGF之间的分歧和这些升高的温度的实验数据表明，不可忽略的贡献，从其他模式有助于TBC，不占在这些谐波形式主义的基本假设，如非弹性散射。考虑到这些ZnO/GAN界面的高质量，这些结果提供了一个宝贵的关键和定量评估的准确性的假设，在当前的计算方法的最先进的预测声子TBC跨界面。
