Deposition of Pd Nanoparticles on InP by Electrophoresis: Dependence on Electrode Polarity

Layers of nanoparticles deposited onto n-type InP single crystals were prepared by electrophoresis from colloid solutions with reverse micelles-containing Pd nanoparticles. Pd nanoparticles in colloid solutions were monitored by transmission electron microscopy and by optical absorption of Pd surface plasmons. Two types of layers were prepared by electrophoresis with an InP wafer placed on the positive electrode or on the negative electrode, respectively. The layers showed a large distinctness between conductivities in axial and lateral direction. The layers were studied by secondary ions mass spectroscopy and atomic force microscopy. It was shown that only the layers deposited on the positive electrode contained Pd nanoparticles. Diodes were prepared on InP wafers with both types of deposited layers, and their current-voltage characteristics and admittance-frequency characteristics were studied at room temperature. Diodes-containing Pd nanoparticles providing large values of Schottky barrier height 0.856 eV appear to be suitable for making sensitive sensors of hydrogen gas in the air.