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 well‐chosen 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 of the n‐GaAs/Ni contacts appeared to increase as a function of time, leading to values of which were dependent on the deposition potential . 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 . 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. © 1999 The Electrochemical Society. All rights reserved.