The incorporation of indium in GaN (0001) surfaces in dependence of strain is investigated by combining molecular beam epitaxy (MBE) growth, quantitative transmission electron microscopy and density functional theory (DFT) calculations. Growth experiments were conducted on GaN, as well as on 30 layers, coherently overgrown by GaN. Despite the only 0.6 in-plane lattice constant of GaN provided by the In0.19Ga0.81N buffer, our experiments reveal that the In incorporation increases by more than a factor of two for growth on the In0.19Ga0.81N buffer, as compared to growth on GaN. DFT calculations reveal that the decreasing chemical potential due to the reduced lattice mismatch stabilizes the In-N bond at the surface. Depending on the growth conditions (metal-rich or N-rich), this promotes the incorporation of higher In contents into a coherently strained layer and inhibits thermal decomposition. As a consequence of the different surface reconstructions, metal-rich MBE growth may be considered as being more favorable for achieving higher In compositions on relaxed InxGa1-xN buffers.

中文翻译：

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应变对铟在（0001）GaN中掺入的影响

通过结合分子束外延（MBE）生长，定量透射电子显微镜和密度泛函理论（DFT）计算，研究了铟在GaN（0001）表面中的应变依赖性。在GaN以及30层上进行了生长实验，这些层连贯地被GaN长满。尽管In0.19Ga0.81N缓冲液提供的GaN仅有0.6的面内晶格常数，但我们的实验表明，与In0.19Ga0.81N缓冲液相比，In的掺入增加了两倍以上，从而在In0.19Ga0.81N缓冲液中生长在GaN上生长。DFT计算表明，由于晶格失配减少，化学势下降，使表面的In-N键稳定。根据生长条件（富金属或富氮），这促进了较高的In含量结合到相干应变层中，并抑制了热分解。由于不同的表面重构，可以认为富金属的MBE生长对于在松弛的InxGa1-xN缓冲液上获得更高的In组成更有利。