title: Long minority carrier diffusion lengths in bridged silicon nanowires.
abstract: Nanowires have large surface areas that create new challenges for their optoelectronic applications. Lithographic processes involved in device fabrication and substrate interfaces can lead to surface defects and substantially reduce charge carrier lifetimes and diffusion lengths. Here, we show that using a bridging method to suspend pristine nanowires allows for circumventing detrimental fabrication steps and interfacial effects associated with planar device architectures. We report electron diffusion lengths up to 2.7 μm in bridged silicon nanowire devices, much longer than previously reported values for silicon nanowires with a diameter of 100 nm. Strikingly, electron diffusion lengths are reduced to only 45 nm in planar devices incorporating nanowires grown under the same conditions. The highly scalable silicon nanobridge devices with the demonstrated long diffusion lengths may find exciting applications in photovoltaics, sensing, and photodetectors.
authors.affiliation: Department of Physics and ‡Department of Electrical and Computer Engineering and Center for Nano and Micro Manufacturing, University of California , Davis, California 95616, United States.
authors.forename: M
authors.initials: M
authors.lastname: Triplett
authors.forename: Y
authors.initials: Y
authors.lastname: Yang
authors.forename: F
authors.initials: F
authors.lastname: Léonard
authors.forename: A Alec
authors.initials: AA
authors.lastname: Talin
authors.forename: M Saif
authors.initials: MS
authors.lastname: Islam
authors.forename: D
authors.initials: D
authors.lastname: Yu
keywords: Nanowire; minority carrier diffusion length; scanning photocurrent microscopy; surface effect