Spectroellipsometric Study of the Electrochemical Modification of InP

In the cathodic decomposition of InP , which occurs during hydrogen evolution, an indium rich film grows on the surface of the semiconductor. Subsequently this film undergoes transformations between oxidized and reduced forms following the electrode polarization. An in situ spectroellipsometric study of these transformations was carried out. From these measurements it is possible to obtain both the thickness and the dielectric function of the film. Using the effective medium approximation, the components of the two forms of film are identified: indium oxide and solution in the oxidized stage, indium and solution in the reduced one. These results show that spectroellipsometry is a method well suited to characterize in situ the electrochemical surface modifications.