Electrical Engineering Department , University of California at Los Angeles, Los Angeles, California 90095, United States.
Nano Lett. 2011 Jun 8;11(6):2490-4. doi: 10.1021/nl200965j. Epub 2011 May 23.
Photovoltaic devices using GaAs nanopillar radial p-n junctions are demonstrated by means of catalyst-free selective-area metal-organic chemical vapor deposition. Dense, large-area, lithographically defined vertical arrays of nanowires with uniform spacing and dimensions allow for power conversion efficiencies for this material system of 2.54% (AM 1.5 G) and high rectification ratio of 213 (at ±1 V). The absence of metal catalyst contamination results in leakage currents of ∼236 nA at -1 V. High-resolution scanning photocurrent microscopy measurements reveal the independent functioning of each nanowire in the array with an individual peak photocurrent of ∼1 nA at 544 nm. External quantum efficiency shows that the photocarrier extraction highly depends on the degenerately doped transparent contact oxide. Two different top electrode schemes are adopted and characterized in terms of Hall, sheet resistance, and optical transmittance measurements.
采用无催化剂选择性区域金属有机化学气相沉积法制备了 GaAs 纳米柱径向 p-n 结光伏器件。密集、大面积、具有光刻定义的垂直纳米线阵列，具有均匀的间距和尺寸，使该材料系统的功率转换效率达到 2.54%（AM 1.5 G），整流比高达 213（在 ±1 V 时）。由于没有金属催化剂的污染，在 -1 V 时泄漏电流约为 236 nA。高分辨率扫描光电流显微镜测量显示，阵列中的每根纳米线都能独立工作，在 544nm 时单个峰值光电流约为 1nA。外量子效率表明，光生载流子的提取高度依赖于简并掺杂的透明接触氧化物。采用了两种不同的顶电极方案，并通过霍尔、薄层电阻和光透射率测量进行了表征。
