Layers of Metal Nanoparticles on Semiconductors Deposited by Electrophoresis from Solutions with Reverse Micelles

Abstract

Pd nanoparticles were prepared with reverse micelles of water/AOT/isooctane solution and deposited onto silicon or InP substrates by electrophoresis. A large change of capacitance-voltage characteristics of mercury contacts on a semiconductor was found after Pd deposition. This change could be modified when the Pd deposition is followed by a partial removal of the deposited AOT. The deposited Pd nanoparticles were investigated by optical mictroscopy, SIMS and SEM. Finally, Schottky diodes with barrier height as high as 1.07 eV were prepared by deposition of Pd nanoparticles on n-type InP and by a partial removal of superfluous AOT. These diodes are prospective structures for further testing as hydrogen sensors.

Electrophoretic deposition of reverse micelle metal nanoparticles

“…Similar TEM images of spherical 10 nm diameter Pd nanoparticles have been observed in thin films prepared from solutions with Pd having less dispersion of 10 % [7].…”

“…We have also tested the diodes for their sensitivity on hydrogen. The results of the measurements and testing have been shown in our previous papers [7,8,12]. Diodes with Pd nanoparticles deposited with the A type polarity showed a significant sensitivity on the hydrogen-nitrogen mixture while those deposited with the C type polarity showed the sensitivity of one or two orders of magnitude smaller.…”

“…Further research in this direction is needed as electrophoretic deposition is gaining increasing interest as a processing technique for production of nanometer scaled layers [6]. We have reported the deposition of Pd nanoparticles coated in reverse micelles by electrophoresis from colloid solutions in isooctane on InP surface acting as a positive electrode [7,8]. The reverse micelles were formed by sodium bis-(2-ethylhexyl) sulfoccinate (AOT).…”

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

“…Colloid solutions of Pd nanoparticles in isooctane were prepared from water solutions of PdCl 2 and hydrazine in reverse micelles of sodium-di-2-ethylhexylsufosuccinate (AOT) [8]. The molar ratio of water to AOT was 10, and the AOT concentration was 1.0 M. First, the stoichiometric ratio of PdCl 2 and hydrazine was used with the intention of having no leftovers of PdCl 2 or hydrazine, when the reducing chemical reaction was completed.…”

“…In such a case, only inhomogeneous electric field could drive metal particles in the direction of the field gradient, due to induced electric dipole moments [7]. However, the deposition of Pd nanolayers by electrophoresis from colloid solutions with reverse micelles-containing Pd nanoparticles has been reported on InP surface [8] as positive electrode in a cell with the homogeneous electric field. Apparently, there are other ingredients in a reverse micelle solution besides metal particles, which have to be considered.…”