Kim Jungkil, Oh Si Duk, Kim Ju Hwan, Shin Dong Hee, Kim Sung, Choi Suk-Ho
Department of Applied Physics, College of Applied Science, Kyung Hee University, Yongin 446-701, Korea.
Sci Rep. 2014 Jun 20;4:5384. doi: 10.1038/srep05384.
Wafer-scale graphene/Si-nanowire (Si-NW) array heterostructures for molecular sensing have been fabricated by vertically contacting single-layer graphene with high-density Si NWs. Graphene is grown in large scale by chemical vapour deposition and Si NWs are vertically aligned by metal-assisted chemical etching of Si wafer. Graphene plays a key role in preventing tips of vertical Si NWs from being bundled, thereby making Si NWs stand on Si wafer separately from each other under graphene, a critical structural feature for the uniform Schottky-type junction between Si NWs and graphene. The molecular sensors respond very sensitively to gas molecules by showing 37 and 1280% resistance changes within 3.5/0.15 and 12/0.15 s response/recovery times under O2 and H2 exposures in air, respectively, highest performances ever reported. These results together with the sensor responses in vacuum are discussed based on the surface-transfer doping mechanism.
通过使单层石墨烯与高密度硅纳米线垂直接触，制备出了用于分子传感的晶圆级石墨烯/硅纳米线（Si-NW）阵列异质结构。石墨烯通过化学气相沉积法大规模生长，硅纳米线通过硅片的金属辅助化学蚀刻垂直排列。石墨烯在防止垂直硅纳米线的尖端聚集方面起着关键作用，从而使硅纳米线在石墨烯下彼此分开地立在硅片上，这是硅纳米线与石墨烯之间均匀肖特基型结的关键结构特征。这些分子传感器对气体分子非常敏感，在空气中分别暴露于氧气和氢气时，在3.5/0.15秒和12/0.15秒的响应/恢复时间内显示出37%和1280%的电阻变化，这是迄今报道的最高性能。基于表面转移掺杂机制讨论了这些结果以及在真空中的传感器响应。
