Photodissolution of n-GaAs electrodes under laser illumination: control ofthe etching profile

The etching profiles of n-GaAs electrodes are controlled under laser illumi nation and anodic polarization. Depending on the incident light power and p H of the solution two etching profiles are obtained: at strong alkali or ac id pH the photon Aux Limits the photodissolution of GaAs. The etching profi le is Gaussian, reproducing the photon distribution of the laser. This etch ing profile is associated with an immediate and constant photocurrent, At i ntermediate pH, the growth of an oxide layer limits the photodissolution of n-GaAs. Therefore we obtained a flat bottom etching profile related to a d ecrease of the photocurrent to a steady state.