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Title: Photoelectrochemistry of Semiconductor Nanowire Arrays

Abstract

This project supported research on the growth and photoelectrochemical characterization of semiconductor nanowire arrays, and on the development of catalytic materials for visible light water splitting to produce hydrogen and oxygen. Silicon nanowires were grown in the pores of anodic aluminum oxide films by the vapor-liquid-solid technique and were characterized electrochemically. Because adventitious doping from the membrane led to high dark currents, silicon nanowire arrays were then grown on silicon substrates. The dependence of the dark current and photovoltage on preparation techniques, wire diameter, and defect density was studied for both p-silicon and p-indium phosphide nanowire arrays. The open circuit photovoltage of liquid junction cells increased with increasing wire diameter, reaching 350 mV for micron-diameter silicon wires. Liquid junction and radial p-n junction solar cells were fabricated from silicon nano- and microwire arrays and tested. Iridium oxide cluster catalysts stabilized by bidentate malonate and succinate ligands were also made and studied for the water oxidation reaction. Highlights of this project included the first papers on silicon and indium phosphide nanowire solar cells, and a new procedure for making ligand-stabilized water oxidation catalysts that can be covalently linked to molecular photosensitizers or electrode surfaces.

Authors:
;
Publication Date:
Research Org.:
The Pennsylvania State University
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
967083
Report Number(s):
DOE/ER/15749-3
DOE Contract Number:
FG02-05ER15749
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
08 HYDROGEN; semiconductor; nanowire; hydrogen; photoelectrochemistry

Citation Formats

Mallouk, Thomas E, and Redwing, Joan M. Photoelectrochemistry of Semiconductor Nanowire Arrays. United States: N. p., 2009. Web. doi:10.2172/967083.
Mallouk, Thomas E, & Redwing, Joan M. Photoelectrochemistry of Semiconductor Nanowire Arrays. United States. doi:10.2172/967083.
Mallouk, Thomas E, and Redwing, Joan M. 2009. "Photoelectrochemistry of Semiconductor Nanowire Arrays". United States. doi:10.2172/967083. https://www.osti.gov/servlets/purl/967083.
@article{osti_967083,
title = {Photoelectrochemistry of Semiconductor Nanowire Arrays},
author = {Mallouk, Thomas E and Redwing, Joan M},
abstractNote = {This project supported research on the growth and photoelectrochemical characterization of semiconductor nanowire arrays, and on the development of catalytic materials for visible light water splitting to produce hydrogen and oxygen. Silicon nanowires were grown in the pores of anodic aluminum oxide films by the vapor-liquid-solid technique and were characterized electrochemically. Because adventitious doping from the membrane led to high dark currents, silicon nanowire arrays were then grown on silicon substrates. The dependence of the dark current and photovoltage on preparation techniques, wire diameter, and defect density was studied for both p-silicon and p-indium phosphide nanowire arrays. The open circuit photovoltage of liquid junction cells increased with increasing wire diameter, reaching 350 mV for micron-diameter silicon wires. Liquid junction and radial p-n junction solar cells were fabricated from silicon nano- and microwire arrays and tested. Iridium oxide cluster catalysts stabilized by bidentate malonate and succinate ligands were also made and studied for the water oxidation reaction. Highlights of this project included the first papers on silicon and indium phosphide nanowire solar cells, and a new procedure for making ligand-stabilized water oxidation catalysts that can be covalently linked to molecular photosensitizers or electrode surfaces.},
doi = {10.2172/967083},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2009,
month =
}

Technical Report:

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  • Semiconductor photoelectrochemical reactions are investigated. A model of the charge transport processes in the semiconductor, based on semiconductor device theory, is presented. It incorporates the nonlinear processes characterizing the diffusion and reaction of charge carriers in the semiconductor. The model is used to study conditions limiting useful energy conversion, specifically the saturation of current flow due to high light intensity. Numerical results describing charge distributions in the semiconductor and its effects on the electrolyte are obtained. Experimental results include: an estimate rate at which a semiconductor photoelectrode is capable of converting electromagnetic energy into chemical energy, the effect of cellmore » temperature on the efficiency, a method for determining the point of zero zeta potential for macroscopic semiconductor samples, a technique using platinized titanium dioxide powders and ultraviolet radiation to produce chlorine, bromine, and iodine from solutions containing their respective ions, the photoelectrochemical properties of a class of layered compounds called transition metal thiophosphates, and a technique used to produce high conversion efficiency from laser radiation to chemical energy.« less
  • The heatsink requirements for coherent operation of laser-diode arrays are examined through thermal analysis of semi-infinite heatsinks and the phase locking of laser diodes. It is shown that mounting laser-diode arrays at the edge of semi-infinite copper heatsinks results in temperature variations between individual laser-diode elements that are too large to permit coherent operation except at relatively low power levels. It is also shown that the use of diamond and shaped heartsinks makes it possible to operate large arrays coherently to high optical output levels. 5 refs., 7 figs., 2 tabs.
  • Principles of the design of integrated chemical systems based on semiconductor materials for the photoelectrochemical utilization of solar energy to drive useful chemical reactions are described. The use of different support materials, such as Nafion and silica, to prepare particulate systems is discussed. Systems with very small (Q- ) particles are described. Charging of these particles is proposed as an important factor in the determination of particle energetics (optical band gap and potentials of photogenerated electrons and holes).
  • Measurements were made of noise in laser arrays, both commercial gain-guided and experimental 10 element index-guided. Relative Intensity Noise (RIN) was found to be comparable to single element gain guided arrays, with approximately 15dB more noise than from a distributed feedback (DFB) laser. Comparable results for gain-guided and index-guided lasers, with supporting theoretical studies, indicate that mode competition is probably the source of the increased noise. Because the arrays produce more power, the increased noise does not necessarily degrade the signal-to-noise ratio. The results of this study indicate that if the system is operating in the receiver-noise-limited regime (<0.1 milliwattsmore » of detected optical power), use of an array will increase the overall signal-to-noise ratio. It was also shown that a reduction in laser noise can be achieved by low frequency modulation. For example, modulation at 10 MHz resulted in a decrease in noise by 5 to 10 dB at 100 MHz.« less
  • This dissertation presents the experimental study of quantum-well heterostructures in the III-V compound semiconductor system of (Al,Ga)As/GaAs. This study was conducted with a view to applying these structures in heterostructure lasers; specifically, phase-locked laser arrays. Broad-area lasers fabricated from the quantum-well microstructures exhibited threshold current densities as low as 200 Amp/sq. cm. The major contribution of this work is a new monolithic laser array structure that achieves phase-locking through coupling by diffraction in a central mode-mixing region where the light is unguided. The propagating eigenmodes are index-guided on either side of the mode-mixing region in parallel-element ridge waveguides. The newmore » array displays narrow, single-lobe far-field patterns. The narrowest far-field pattern observed is 2/sup 0/ wide. An analytic model that explains the characteristics of the observed far-field patterns is presented. This model is developed from a premise with experimental basis.« less