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Surface Morphology-Dependent Photoelectrochemical Properties of One-Dimensional Si Nanostructure Arrays Prepared by Chemical Etching
journal contribution
posted on 2013-06-12, 00:00 authored by Shao-long Wu, Long Wen, Guo-an Cheng, Rui-ting Zheng, Xiao-ling WuMaximizing the optical absorption
of one-dimensional Si nanostructure
arrays (1DSiNSAs) is desirable for excellent performance of 1DSiNSA-based
optoelectronic devices. However, a quite large surface-to-volume ratio
and enhanced surface roughness are usually produced by modulation
of the morphology of the 1DSiNSAs prepared in a top-down method to
improve their optical absorption. Surface recombination is mainly
determined by the surface characteristics and significantly affects
the photogenerated carrier collection. In this paper, we systematically
investigated the photoelectrochemical characteristics of 1DSiNSAs
with various morphologies prepared by the metal-assisted chemical
etching of Si wafers. Our results show that the saturation photocurrent
density and photoresponsivity of 1DSiNSAs first increased and then
gradually decreased with an increasing etching time, while the reflection
spectrum was gradually suppressed to the measurable minimum. To identify
the behaviors of the photoresponsivity and optical absorption of the
various 1DSiNSAs, we analyzed the morphology, structure, and minority-carrier
lifetime. Additionally, device physics simulations were used to confirm
the significance of surface recombination. We proposed that future
directions for the design of nanostructure-based optoelectronic devices
should include not only strong optical absorption but also low surface
carrier recombination. High-performance devices could be obtained
only by balancing the requirements for light absorption and photogenerated
carrier collection.