Electropolishing of GaAs

In order to find out the mirror-finish conditions for GaAs substrates with non-damage, which are used for diodes in ultra high frequencies with very high speeds, a disc type electro-polishing machine is made trially, and the suitable electrolytes, polishing conditions and stock removals are pursued from the viewpoint of surface quality. The results obtained are as follows : (1) The electrolytes suitable for the disc type electropolishing are 0.25% KON or NaOH with the same concentration. (2) Roughness of 0.02μ in maximum height, independent of crystal orientations, is obtained with the finishing rate from 3 to 6times as high as that of chemical polishing in the case of p-type materials. (3) Electrochemical approaches are necessary for polishing ntype materials electrolytically due to their inferior roughness of 0.1μ. (4) Clear Kikuchi's lines are found to be exposed on the electropolished surfaces according to the estimation by electron diffraction.