Institut Néel CNRS/UJF UPR2940, BP 166, 25 rue des Martyrs, 38042 Grenoble cedex 9, France.
Nano Lett. 2012 Nov 14;12(11):5691-6. doi: 10.1021/nl302890f. Epub 2012 Oct 5.
GaN nanowires (NWs) with an AlN insertion were studied by correlated optoelectronic and aberration-corrected scanning transmission electron microscopy (STEM) characterization on the same single NW. Using aberration-corrected annular bright field and high angle annular dark field STEM, we identify the NW growth axis to be the N-polar [000-1] direction. The electrical transport characteristics of the NWs are explained by the polarization-induced asymmetric potential profile and by the presence of an AlN/GaN shell around the GaN base of the wire. The AlN insertion blocks the electron flow through the GaN core, confining the current to the radial GaN outer shell, close to the NW sidewalls, which increases the sensitivity of the photocurrent to the environment and in particular to the presence of oxygen. The desorption of oxygen adatoms in vacuum leads to a reduction of the nonradiative surface trap density, increasing both dark current and photocurrent.
我们通过对同一根纳米线进行相关光电和像差校正扫描透射电子显微镜（STEM）表征，研究了具有氮化铝插入的氮化镓纳米线（NWs）。使用像差校正的环形明场和高角度环形暗场 STEM，我们确定 NW 的生长轴为 N 极性 [000-1] 方向。通过极化诱导的非对称势分布和 NW 基的 GaN 外壳周围存在的氮化铝/氮化镓壳，解释了 NW 的电输运特性。氮化铝插入物阻止了电子在 GaN 核中的流动，将电流限制在靠近 NW 侧壁的 GaN 外壳的径向部分，这增加了光电流对环境的敏感性，特别是对氧的存在的敏感性。在真空中，氧吸附原子的解吸会导致非辐射表面陷阱密度降低，从而增加暗电流和光电流。
