Fabrication of GaAs symmetric pyramidal mesas prepared by wet-chemical etching using AlAs interlayer

We present a wet-chemical-etching method developed for the preparation of GaAs four-sided pyramid-shaped mesas. The method uses a fast lateral etching of AlAs interlayer that influences the cross-sectional profiles of etched structures. We have tested the method using H3PO4:H2O2:H2O etchant for the (100) GaAs patterning. The sidewalls of the prepared pyramidal structures together with the (100) bottom facet formed the cross-sectional angles 25 degrees and 42 degrees for mask edges parallel, resp. perpendicular to {011} cleavage planes. For mask edges turned in 45 degrees according to the cleavage planes, 42 degrees cross-sectional angles were obtained. Using the method, symmetric and more than 10-mum-high GaAs "Egyptian" pyramids with smooth tilted facets were prepared. (C) 2002 American Institute of Physics.