Electroreduction of Co2 +  and Ni2 +  at III-V Semiconductors and Properties of the Semiconductor/Metal Interfaces Formed

Abstract

The electrochemical deposition of Ni and Co on GaAs and GaP at pH 5 was investigated by means of cyclic voltammetry and rotating disk voltammetry. The current-potential behavior of the two semiconductors in dilute metal ion solutions appeared to be different: at n-GaP, a stepwise reduction of the metal ions was observed, whereas at n-GaAs this was not the case. This observation can be explained on the basis of two alternative reaction mechanisms for the reduction of the monovalent intermediate. Under wellchosen conditions of deposition potential and metal ion concentration, it appeared to be possible to form adherent n-GaAs/Co, n-GaAs/Ni, and n-GaP/Co Schottky contacts with good rectifying properties. The barrier height ⌽ B of the n-GaAs/Ni contacts appeared to increase as a function of time, leading to values of ⌽ B which were dependent on the deposition potential V D . At n-GaAs/Co and n-GaP/Co junctions, this aging effect was absent, leading to values of the barrier height which were independent of V D . It was further observed that the occurrence of side reactions during metal deposition may exert a great influence upon the properties of the metal/semiconductor junctions formed.

The voltammetric response of bipolar cells: Reversible electron transfer

“…A parallel can be drawn between the above case and the electrodeposition of metals on semiconducting materials, since in the latter case the response can be limited by the solution phase process, or by charge carriers in the semiconductor, depending on how the applied potential drops over the Helmholtz and spacecharge layers [24]. For a multi-electron reaction this can result in the stepwise reduction of the metal ion, or the deposition on sites with different energy [25,26].…”

Electrochemical formation and properties of n-GaAs/Au and n-GaAs/Ag Schottky barriers: Influence of surface composition upon the barrier height

“…Although these contacts are usually formed by methods based upon metal deposition from the gas phase, 1 electrochemical procedures have also been reported for fabricating semiconductor=metal Schottky barriers. [2][3][4][5][6][7][8][9][10][11][12] In several cases (e.g. Cu, 3,6,7 Co, 4,9 Bi, 11 Pt, 4 Pb 12 and Au 5,12 upon n-GaAs, and Co upon n-GaP 9 ), the barrier height F B was found to be larger for electrochemically formed barriers than for barriers produced by vacuum deposition.…”

“…[2][3][4][5][6][7][8][9][10][11][12] In several cases (e.g. Cu, 3,6,7 Co, 4,9 Bi, 11 Pt, 4 Pb 12 and Au 5,12 upon n-GaAs, and Co upon n-GaP 9 ), the barrier height F B was found to be larger for electrochemically formed barriers than for barriers produced by vacuum deposition. In order to explain this observation, studies have been performed in which the metal was systematically deposited electrochemically upon a semiconductor surface under different conditions, after which the properties of the junctions formed were compared to those of Schottky contacts formed under vacuum conditions.…”

“…In order to explain this observation, studies have been performed in which the metal was systematically deposited electrochemically upon a semiconductor surface under different conditions, after which the properties of the junctions formed were compared to those of Schottky contacts formed under vacuum conditions. 7,9 The differences in value of F B could be explained on the basis of a difference in chemical composition of the metal=semiconductor interface in the respective cases. 7,9 It further appeared that, for the electrochemically formed contacts, the chemical composition of the interface was strongly determined by the electrochemistry, i.e.…”

Electrochemical formation of GaAs/Bi Schottky barriers

“…Aging of semiconductor/metal junctions has been reported previously and is frequently ascribed to interfacial reactions. [19][20][21][22] For bismuth films deposited at Ϫ0.2 V the deposition is under kinetic control, as can be inferred from Fig. 1, and under these conditions the deposition rate is relatively slow so that films are expected to be compact with relatively large FIG.…”