NONLINEAR PHOTOELECTROCHEMICAL SYSTEMS

The nonlinear effects were considered which arise at the semiconductor /electrolyte solution interface under conditions of modulated illumina tion (at the same time with light of constant and of variable intensit y). These effects are due to a redistribution of potential between the Helmholtz and space-charge layer, to photostimulated surface recombin ation, and to a change in trapping coefficient of the surface states f or minority carriers. Photocurrent diagrams were constructed for these three mechanisms of nonlinearity at different levels of constant back ground illumination l, In the complex plane, the frequency spectrum of the photocurrent shifts along the real photocurrent axis with increas ing l, while the frequency at the maximum of the imaginary part (the r eciprocal of relaxation time) increases when nonlinearity is present. Experimental possibilities for separation of the different nonlinear e ffects were discussed.