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Title: Dense nanoimprinted silicon nanowire arrays with passivated axial p-i-n junctions for photovoltaic applications

We report on the fabrication and photovoltaic characteristics of vertical arrays of silicon axial p-i-n junction nanowire (NW) solar cells grown by vapor-liquid-solid (VLS) epitaxy. NW surface passivation with silicon dioxide shell is shown to enhance carrier recombination time, open-circuit voltage (V{sub OC}), short-circuit current density (J{sub SC}), and fill factor (FF). The photovoltaic performance of passivated individual NW and NW arrays was compared under 532 nm laser illumination with power density of ∼10 W/cm{sup 2}. Higher values of V{sub OC} and FF in the NW arrays are explained by enhanced light trapping. In order to verify the effect of NW density on light absorption and hence on the photovoltaic performance of NW arrays, dense Si NW arrays were fabricated using nanoimprint lithography to periodically arrange the gold seed particles prior to epitaxial growth. Compared to sparse NW arrays fabricated using VLS growth from randomly distributed gold seeds, the nanoimprinted NW array solar cells show a greatly increased peak external quantum efficiency of ∼8% and internal quantum efficiency of ∼90% in the visible spectral range. Three-dimensional finite-difference time-domain simulations of Si NW periodic arrays with varying pitch (P) confirm the importance of high NW density. Specifically, due to diffractive scattering and lightmore » trapping, absorption efficiency close to 100% in the 400–650 nm spectral range is calculated for a Si NW array with P = 250 nm, significantly outperforming a blanket Si film of the same thickness.« less
Authors:
; ; ; ;  [1] ; ;  [2] ;  [3] ;  [4]
  1. Department of Physics and School of Engineering, Brown University, Providence, Rhode Island 02912 (United States)
  2. Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742 (United States)
  3. (United States)
  4. Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)
Publication Date:
OSTI Identifier:
22399352
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 12; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 77 NANOSCIENCE AND NANOTECHNOLOGY; ABSORPTION; COMPARATIVE EVALUATIONS; COMPUTERIZED SIMULATION; CURRENT DENSITY; ELECTRIC POTENTIAL; EPITAXY; FILL FACTORS; GOLD; NANOWIRES; PHOTOVOLTAIC EFFECT; QUANTUM EFFICIENCY; RECOMBINATION; SEMICONDUCTOR JUNCTIONS; SILICON; SILICON OXIDES; SOLAR CELLS; THIN FILMS; TRAPPING; VISIBLE RADIATION