Document Detail

Bias Dependence of Sub-Bandgap Light Detection for Core-Shell Silicon Nanowires.
MedLine Citation:
PMID:  23098159     Owner:  NLM     Status:  Publisher    
We experimentally demonstrate a vertically arrayed silicon nanowire-based device that exhibits voltage dependence of photoresponse to infrared sub-bandgap optical radiation. The device is fabricated using a proximity solid-state phosphorous diffusion method to convert the surface areas of highly boron-doped silicon nanowires into n-type, thus forming a radial core-shell p-n junction structure. Prominent photoresponse from such core-shell Si nanowires is observed under sub-bandgap illumination at 1310 nm. The strong bias dependence of the photoresponse and other device characteristics indicates that the sub-bandgap absorption is attributed to the intrinsic properties of core-shell Si nanowires rather than the surface states. The attractive characteristics are based on three physical mechanisms: the Franz-Keldysh effect, quasi-quantum confinement effect, and the impurity-state assisted photon absorption. The first two effects enhance carrier tunneling probability, rendering a stronger wavefunction overlap to facilitate sub-bandgap absorption. The last effect relaxes the k-selection rule by involving the localized impurity states, thus removing the limit imposed by the indirect bandgap nature of Si. The presented device uses single-crystal silicon and holds promise of fabricating nanophotonic systems in a fully CMOS compatible process. The concept and approach can be applied to silicon and other materials to significantly extend the operable wavelength regime beyond the constraint of energy bandgap. KEYWORDS: silicon nanowire, sub-bandgap absorption, nanophotonics, photodetection.
Yuchun Zhou; Yu-Hsin Liu; James Cheng; Yu-Hwa Lo
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-10-25
Journal Detail:
Title:  Nano letters     Volume:  -     ISSN:  1530-6992     ISO Abbreviation:  Nano Lett.     Publication Date:  2012 Oct 
Date Detail:
Created Date:  2012-10-26     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101088070     Medline TA:  Nano Lett     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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