Polenta L, Rossi M, Cavallini A, Calarco R, Marso M, Meijers R, Richter T, Stoica T, Lüth H
CNISM and Physics Department, University of Bologna, V.le Berti-Pichat 6/2, 40127 Bologna, Italy.
ACS Nano. 2008 Feb;2(2):287-92. doi: 10.1021/nn700386w.
GaN nanowires with diameters ranging between 50 and 500 nm were investigated by electrical and photoinduced current techniques to determine the influence of their size on the opto-electronic behavior of nanodevices. The conductivity, photoconductivity, and persistent photoconductivity behavior of GaN nanowires are observed to strongly depend on the wire diameter. In particular, by spectral photoconductivity measurements, three main sub-band-gap optoelectronic transitions were detected, ascribed to the localized states giving rise to the characteristic blue, green, and yellow bands of GaN. Photoconductivity with below-band-gap excitation varies orders of magnitude with the wire diameter, similarly to that observed for near-band-edge excitation. Moreover, yellow-band-related signal shows a superlinear behavior with respect to the band-edge signal, offering new information for the modeling of the carrier recombination mechanism along the nanowires. The photoconductivity results agree well with a model which takes into account a uniform distribution of the localized states inside the wire and their direct recombination with the electrons in the conduction band.
通过电学和光致电流技术对直径在50至500纳米之间的氮化镓纳米线进行了研究，以确定其尺寸对纳米器件光电行为的影响。观察到氮化镓纳米线的电导率、光电导率和持续光电导行为强烈依赖于线径。特别是，通过光谱光电导率测量，检测到三个主要的亚带隙光电跃迁，归因于产生氮化镓特征蓝、绿和黄带的局域态。与近带边激发情况类似，带隙以下激发的光电导率随线径变化几个数量级。此外，与黄带相关的信号相对于带边信号表现出超线性行为，为沿纳米线的载流子复合机制建模提供了新信息。光电导率结果与一个模型很好地吻合，该模型考虑了线内局域态的均匀分布及其与导带中电子的直接复合。
