Study of Stabilization and Surface Recombination on n-GaP Photoelectrodes: Mechanisms and Interrelation

The competition has been studied between three processes occurring with photogenerated holes at the n-GaP/ aqueous electrolyte interface, i.e., reaction with Fe 2+ ions, reaction with GaP itself, and surface recombination. The experimental method used was the rotating ring-disk technique. The influence of the reducing agent concentration, of the light intensity, and of the electrode potential was investigated. The results can be interpreted on the basis of models, in which the stabilization process, and under certain circumstances also the recombination process, takes place tl~rough surface intermediates of the photoanodic decomposition reaction. In connection with the possible use of photoelectro-chemical cells for solar energy conversion, there has recently been a considerable interest in the problem of the prevention of anodic decomposition of i l luminated n-type semiconductor electrodes by means of compet-ing hole reactions with reducing agents added to the solution. In the case of n-type I I I-V semiconductors such as GaAs, GaP, and InP, it has been shown ex