We report a new technique of using a floating-gate capacitive structure to measure the electrochemical potential difference between a reference conductor and the material in question as a function of some external parameter. It is illustrated by measurements on two two-dimensional systems: Si metal-oxide-semiconductor structures and (Ga,Al)As:GaAs heterostructures.

• Received 26 August 1985

DOI:https://doi.org/10.1103/PhysRevB.33.1529