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Issue 5, 2010
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High sensitivity hydrogen sensing with Pt-decorated porous gallium nitride prepared by metal-assisted electroless etching

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Abstract

A unique hydrogen sensor structure based on Pt-decorated porous gallium nitride (PGaN) was fabricated by a two-step process consisting of metal-assisted electroless etching to produce PGaN with highly anisotropic pores followed by electroless deposition of Pt in the pores from an ammoniacal PtCl62 solution. The Pt-decorated PGaN structure contains 50–100 nm diameter nanopores which are 400 nm to 1 µm deep and filled with Pt islands. Both electroless etching and deposition steps are done in solution and allow for large-scale production. An AC four-point probe conductivity measurement was implemented at f = 1 kHz, a frequency where the impedance of PtPGaN is nearly entirely resistive, and the change in conductance upon H2 exposure was measured for three sample types: PGaN with a surface sputtered layer of Pt only; unetched GaN (CGaN) with both sputtered and electrolessly deposited Pt; and PGaN with both sputtered and electrolessly deposited Pt. The hydrogen sensing performance of the Pt-filled PGaN sensor was more than an order of magnitude better than either of the other two sample types under all experimental conditions, an observation attributed to the significant increase in PtGaN interfacial area in the electrolessly decorated PGaN samples, exhibiting a response to H2 concentrations as low as 1 ppm. The conductance changes are ascribed to adsorption-induced changes in interfacial polarization that produce changes in band bending and thus to the width of the space charge region near the PtGaN interface.

Graphical abstract: High sensitivity hydrogen sensing with Pt-decorated porous gallium nitride prepared by metal-assisted electroless etching

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Publication details

The article was received on 11 Dec 2009, accepted on 19 Mar 2010 and first published on 06 Apr 2010


Article type: Paper
DOI: 10.1039/B926182F
Citation: Analyst, 2010,135, 902-907
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    High sensitivity hydrogen sensing with Pt-decorated porous gallium nitride prepared by metal-assisted electroless etching

    B. K. Duan and P. W. Bohn, Analyst, 2010, 135, 902
    DOI: 10.1039/B926182F

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