Light-controlled Anodic oxidation of n-GaAs and its application to preparation of specified active layers for MESFET's

A new technique of anodic oxidation of n-GaAs is presented, whose principle is based upon the photo-avalanche multiplication effect during anodic oxidation under light illumination. An attractive feature of this technique is that the impurity concentration-thickness product of an n-GaAs epitaxial layer on a semi-insulating GaAs substrate can be automatically and precisely controlled to a desired value without knowing the initial thickness and the impurity concentration of the epitaxial layer. This etching technique has been successfully applied to the GaAs MESFET fabrication process, where the well-controlled drain saturation current and pinchoff voltage are obtainable simply by varying the illuminating light intensity during anodic oxidation.