Investigation of the C-V behaviour of GaAs-metal and GaAs-electrolyte contacts under forward bias

The electrical characteristics of GaAs-metal and GaAs-electrolyte Schottky barrier diodes have been studied as a function of applied voltage and of frequency, using conventional Schottky barrier C-V analysis and I-V measurements. For forward voltages approaching the flat-band voltage, i.e. the diffusion voltage, the measured capacitance deviates from a linear C -2 versus V dependence, i.e. the C -2 value drops steeply and a 'knee' in the Mott-Schottky plot is observed. This effect is found for the equivalent series capacitance C s as well as for the equivalent parallel capacitance C p , but in a different voltage range. The 'knee' in the C p -2 versus V and in the C s -2 versus V plots is explained. The difference between these two plots is attributed to the forward current.