Direct Heteroepitaxy of Vertical InAs Nanowires on Si Substrates for Broad Band Photovoltaics and Photodetection
Direct Heteroepitaxy of Vertical InAs Nanowires on Si Substrates for Broad Band Photovoltaics and Photodetection
复制标题
DOI：
10.1021/nl901270n
复制
发表时间：
2009-08-01
期刊：
影响因子：
10.8
通讯作者：
Wang, Deli
中科院分区：
文献类型：
--
作者：
Wei, Wei;Bao, Xin-Yu;Wang, Deli
采用金属-有机化学气相沉积技术，在Si(111)衬底上实现了无催化剂、直接异质外延生长垂直InAs纳米线。纳米线显示出非常均匀的直径和闪锌矿晶体结构。利用n型InAs纳米线与p型硅衬底界面处形成的异质结制作了具有良好整流比和低反向漏电流的垂直阵列光电二极管器件。从理论和实验上研究了在黑暗和AM 1.5照明条件下，异质结上的电流输运随温度的变化。当工作在光伏模式下时，开路电压随温度的降低而线性增加，而能量转换效率却非单调变化，在110K时达到最大值2.5%。对纳米线/衬底异质结的模拟结果与实验结果吻合较好，可以确定InAs纳米线与硅之间的导带偏移量为0.10-0.15 eV。该器件的外量子效率和光响应度曲线显示出从可见光到红外区的广泛光谱响应，表明其作为宽带光伏电池或可见光-红外双波段光电探测器具有潜在的应用前景。
Catalyst-free, direct heteroepitaxial growth of vertical InAs nanowires on Si(111) substrates was accomplished over a large area by metal-organic chemical vapor deposition. Nanowires showed very uniform diameters and a zinc blende crystal structure. The heterojunctions formed at the interface between the n-type InAs nanowires and the p-type Si substrate were exploited to fabricate vertical array photodiode devices which showed an excellent rectification ratio and low reverse leakage current. Temperature-dependent current transport across the heterojunctions was studied theoretically and experimentally in the dark and under AM 1.5 illumination. When operated in photovoltaic mode, the open-circuit voltage was found to increase linearly with decreasing temperature while the energy conversion efficiency changed nonmonotonically with a maximum of 2.5% at 110 K. Modeling of the nanowire/substrate heterojunctions showed good agreement with the experimental observations, and allowed determining the conduction band offset between the InAs nanowires and Si to be 0.10-0.15 eV. The external quantum efficiency and photoresponsivity profiles of the device showed a broad spectral response from the visible to the infrared region, indicating potential applications as a broad band photovoltaic cell or a visible-infrared dual-band photodetector.