Voltage-controlled photoetching of GaAs

The effects of optically generated minority-carrier current on the etching behavior of n-type GaAs in 1-M KOH aqueous solution were studied. It was observed that the etch rate depends on the minority-carrier current flow through the interface, which is controlled by the bias voltage. The etch rate is considerably reduced under open-circuit conditions as compared to short-circuit conditions. This effect simulates a self-limiting photoetching process for the thickness trimming of thin films, which is necessary for several device applications.