Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin, Germany.
Nano Lett. 2015 Jun 10;15(6):3743-7. doi: 10.1021/acs.nanolett.5b00251. Epub 2015 May 29.
Vertical GaN nanowires are grown in a self-induced way on a sputtered Ti film by plasma-assisted molecular beam epitaxy. Both in situ electron diffraction and ex situ ellipsometry show that Ti is converted to TiN upon exposure of the surface to the N plasma. In addition, the ellipsometric data demonstrate this TiN film to be metallic. The diffraction data evidence that the GaN nanowires have a strict epitaxial relationship to this film. Photoluminescence spectroscopy of the GaN nanowires shows excitonic transitions virtually identical in spectral position, line width, and decay time to those of state-of-the-art GaN nanowires grown on Si. Therefore, the crystalline quality of the GaN nanowires grown on metallic TiN and on Si is equivalent. The freedom to employ metallic substrates for the epitaxial growth of semiconductor nanowires in high structural quality may enable novel applications that benefit from the associated high thermal and electrical conductivity as well as optical reflectivity.
通过等离子体辅助分子束外延，在溅射 Ti 膜上以自诱导的方式生长垂直 GaN 纳米线。原位电子衍射和非原位椭圆光度法都表明，Ti 表面暴露于 N 等离子体时会转化为 TiN。此外，椭圆光度法数据表明该 TiN 薄膜为金属性的。衍射数据表明 GaN 纳米线与该薄膜具有严格的外延关系。GaN 纳米线的光致发光谱显示，激子跃迁在光谱位置、线宽和衰减时间上与在 Si 上生长的最先进的 GaN 纳米线几乎完全相同。因此，生长在金属 TiN 和 Si 上的 GaN 纳米线的晶体质量是等效的。在高质量结构的半导体纳米线的外延生长中使用金属衬底的自由度，可能会带来一些新的应用，这些应用将受益于相关的高热导率、电导率和光学反射率。
