Electrochemical Deposition of Bi on GaAs(100).

The electrochemical deposition of bismuth on n-GaAs(100), n + -GaAs(100), and p-GaAs(100) from Bi(NO 3 ) 3 solution is characterized by cyclic voltammetry and impedance measurements. Electron capture at the conduction band forms the rate-determining step in the reduction of Bi 3+ at n-type GaAs. The morphology of the bismuth films is related to the deposition kinetics. The rectifying n-GaAs/Bi Schottky barrier formed on low-doped substrates prevents oxidation of bismuth, whereas tunneling through the space-charge layer allows anodic stripping of Bi on highly doped substrates. Under illumination, electroless deposition of Bi is observed on n-GaAs. Surface-state mediated hole injection is responsible for the slow deposition of Bi on p-GaAs in the dark. Photoassisted nucleation and subsequent growth in the dark results in the formation of continuous thin Bi films on p-GaAs.