Abstract: An interface between a semiconductor substrate/dielectric layer is characterized through measurements of a photocurrent. The photocurrent is induced in the semiconductor substrate by scanning a certain area of the interface with a laser beam and which is collected via a Schottky contact. The Schottky contact is established by inversely biasing a first electrolyte with respect to a potential of the bulk of the semiconductor substrate. The first electrolyte is capable of etching any native or thermal oxide that may exist on the contact area with the semiconductor substrate. The surface potential of the semiconductor substrate/dielectric interface is controlled by a gate electrode established on the dielectric layer by way of a second electrolyte. The second electrolyte is not aggressive to the dielectric material and is biased by an electrode immersed therein with respect to the potential of the bulk of the semiconductor substrate.