Synthesis of nanoporous bismuth films by liquid-phase deposition

Abstract

A liquid phase deposition method involving metal carboxylates has been used to obtain porous bismuth films. Porous morphologies offer the opportunity to interrupt phonon transport without interfering with electron transport, an important consideration for thermoelectric materials. The films were prepared by spin coating a solution of bismuth(III) 2-ethylhexanoate and 5 wt% glycerol in 2-methylpropan-1-ol with subsequent heat treatment in hydrogen between 250 and 270 °C. Thermal decomposition studies established the intermediate and final products associated with the pyrolysis reaction. The porosity of the resulting films varied from 30 to 50% and residual carbon in the film was removed by hydrogen plasma etching. The pores were present in the form of nano-dimensional channels, on the order of 5–10 nm wide, existing between bismuth grains.