Open Access Nano Express

Graphite/InP and graphite/GaN Schottky barriers with electrophoretically deposited Pd or Pt nanoparticles for hydrogen detection

Karel Zdansky

Author Affiliations

Institute of Photonics and Electronics, Academy of Sciences of the Czech Republic, Chaberska 57, Prague 8, 18251, Czech Republic

Nanoscale Research Letters 2012, 7:415  doi:10.1186/1556-276X-7-415

Published: 23 July 2012

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.

Keywords:
Graphite/InP; Graphite/GaN; Hydrogen detection