John P, Gómez Ruiz M, van Deurzen L, Lähnemann J, Trampert A, Geelhaar L, Brandt O, Auzelle T
Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e.V., Hausvogteiplatz 5-7, D-10117 Berlin, Germany.
School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853, United States of America.
Nanotechnology. 2023 Sep 1;34(46). doi: 10.1088/1361-6528/acefd8.
We study the molecular beam epitaxy of AlN nanowires between 950 °C and 1215 °C, well above the usual growth temperatures, to identify optimal growth conditions. The nanowires are grown by self-assembly on TiN(111) films sputtered onto AlO. Above 1100 °C, the TiN film is seen to undergo grain growth and its surface exhibits {111} facets where AlN nucleation preferentially occurs. Modeling of the nanowire elongation rate measured at different temperatures shows that the Al adatom diffusion length maximizes at 1150 °C, which appears to be the optimum growth temperature. However, analysis of the nanowire luminescence shows a steep increase in the deep-level signal already above 1050 °C, associated with O incorporation from the AlOsubstrate. Comparison with AlN nanowires grown on Si, MgO and SiC substrates suggests that heavy doping of Si and O by interdiffusion from the TiN/substrate interface increases the nanowire internal quantum efficiency, presumably due to the formation of a SiNor AlOpassivation shell. The outdiffusion of Si and O would also cause the formation of the inversion domains observed in the nanowires. It follows that for optoelectronic and piezoelectric applications, optimal AlN nanowire ensembles should be prepared at 1150 °C on TiN/SiC substrates and will require ansurface passivation.
我们研究了在950℃至1215℃之间生长氮化铝（AlN）纳米线的分子束外延，该温度远高于通常的生长温度，以确定最佳生长条件。纳米线通过自组装生长在溅射在氧化铝（AlO）上的氮化钛（TiN）（111）薄膜上。在1100℃以上，观察到TiN薄膜发生晶粒生长，其表面呈现出{111}面，AlN优先在这些面上成核。对在不同温度下测量的纳米线伸长率进行建模表明，铝吸附原子的扩散长度在1150℃时达到最大值，这似乎是最佳生长温度。然而，对纳米线发光的分析表明，在1050℃以上，深能级信号就急剧增加，这与从AlO衬底中掺入氧有关。与在硅（Si）、氧化镁（MgO）和碳化硅（SiC）衬底上生长的AlN纳米线进行比较表明，从TiN/衬底界面通过互扩散对硅和氧的重掺杂提高了纳米线的内部量子效率，这可能是由于形成了SiN或AlO钝化壳层。硅和氧的向外扩散也会导致在纳米线中观察到的反转畴的形成。因此，对于光电子和压电应用，应在1150℃下在TiN/SiC衬底上制备最佳的AlN纳米线阵列，并且需要进行表面钝化处理。
