Article

Palladium nanoparticles on InP for hydrogen detection

Department of Physical Electronics, Czech Technical University, V Holesovickach 2, Prague, Czeck Republic. .
Nanoscale Research Letters (Impact Factor: 2.48). 06/2011; 6:410. DOI: 10.1186/1556-276X-6-410
Source: PubMed

ABSTRACT Layers of palladium (Pd) nanoparticles on indium phosphide (InP) were prepared by electrophoretic deposition from the colloid solution of Pd nanoparticles. Layers prepared by an opposite polarity of deposition showed different physical and morphological properties. Particles in solution are separated and, after deposition onto the InP surface, they form small aggregates. The size of the aggregates is dependent on the time of deposition. If the aggregates are small, the layer has no lateral conductance. Forward and reverse I-V characteristics showed a high rectification ratio with a high Schottky barrier height. The response of the structure on the presence of hydrogen was monitored.

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    ABSTRACT: Large attention has been devoted worldwide to the investigation of hydrogen sensors based on various Schottky diodes. We prepared graphite semimetal Schottky contacts on polished n-InP and n-GaN wafers partly covered with nanoparticles of catalytic metals Pd or Pt by applying colloidal graphite. Metal nanoparticles were deposited electrophoretically from colloids prepared beforehand. Deposited nanoparticles were imaged by scanning electron microscopy, atomic force microscopy, and scanning tunneling microscopy on the as-made and annealed-in-vacuum samples. Current-voltage characteristics of prepared Schottky diodes had very high rectification ratios, better than 107 at 1 V. It was shown that the barrier heights of these diodes were equal to the difference between the electron affinity of InP or GaN and the electron work function of the metal Pd or Pt (Schottky-Mott limit). That was a good precondition for the high sensitivity of the diodes to hydrogen, and indeed, high sensitivity to hydrogen, with the detection limit better than 1 ppm, was proved.
    Nanoscale Research Letters 07/2012; 7(1):415. DOI:10.1186/1556-276X-7-415 · 2.48 Impact Factor

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