Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287-1604, USA.
J Am Chem Soc. 2013 Aug 21;135(33):12388-99. doi: 10.1021/ja405726b. Epub 2013 Aug 12.
In this work, we extend our strategy previously developed to synthesize functional, crystalline Si(5-2y)(AlX)y {X = N,P,As} semiconductors to a new class of Ge-III-V hybrid compounds, leading to the creation of (InP)(y)Ge(5-2y) analogues. The compounds are grown directly on Ge-buffered Si(100) substrates using gas source MBE by tuning the interaction between Ge-based P(GeH3)3 precursors and In atoms to yield nanoscale "In-P-Ge3" building blocks, which then confer their molecular structure and composition to form the target solids via complete elimination of H2. The collateral production of reactive germylene (GeH2), via partial decomposition of P(GeH3)3, is achieved by simple adjustment of the deposition conditions, leading to controlled Ge enrichment of the solid product relative to the stoichiometric InPGe3 composition. High resolution XRD, XTEM, EDX, and RBS indicate that the resultant monocrystalline (InP)(y)Ge(5-2y) alloys with y = 0.3-0.7 are tetragonally strained and fully coherent with the substrate and possess a cubic diamond-like structure. Molecular and solid-state ab initio density functional theory (DFT) simulations support the viability of "In-P-Ge3" building-block assembly of the proposed crystal structures, which consist of a Ge parent crystal in which the P atoms form a third-nearest-neighbor sublattice and "In-P" dimers are oriented to exclude energetically unfavorable In-In bonding. The observed InP concentration dependence of the lattice constant is closely reproduced by DFT simulation of these model structures. Raman spectroscopy and ellipsometry are also consistent with the "In-P-Ge3" building-block interpretation of the crystal structure, while the observation of photoluminescence suggests that (InP)(y)Ge(5-2y) may have important optoelectronic applications.
在这项工作中，我们扩展了之前开发的策略，用于合成功能性、结晶 Si(5-2y)(AlX)y {X = N, P, As} 半导体，以用于一类新的 Ge-III-V 混合化合物，从而创造出(InP)(y)Ge(5-2y)类似物。这些化合物使用气体源 MBE 在 Ge 缓冲 Si(100)衬底上直接生长，通过调整基于 Ge 的 P(GeH3)3 前体与 In 原子之间的相互作用，生成纳米级的“In-P-Ge3”构建块，然后通过完全消除 H2，使这些构建块将其分子结构和组成赋予目标固体，从而形成目标固体。通过简单调整沉积条件，可以实现 P(GeH3)3 的部分分解，从而产生反应性锗烯(GeH2)，导致固体产物相对于化学计量比的 InPGe3 组成的 Ge 富集得到控制。高分辨率 XRD、XTEM、EDX 和 RBS 表明，所得的单晶(InP)(y)Ge(5-2y)合金，其中 y = 0.3-0.7，具有四方应变，与衬底完全一致，并具有立方金刚石样结构。分子和固态从头算密度泛函理论（DFT）模拟支持所提出晶体结构的“In-P-Ge3”构建块组装的可行性，这些晶体结构由一个 Ge 母体晶体组成，其中 P 原子形成第三个最近邻亚晶格，并且“In-P”二聚体取向排除了能量不利的 In-In 键合。这些模型结构的 DFT 模拟很好地再现了观察到的晶格常数与 InP 浓度的依赖性。拉曼光谱和椭圆偏振法也与晶体结构的“In-P-Ge3”构建块解释一致，而光致发光的观察表明(InP)(y)Ge(5-2y)可能具有重要的光电应用。
