Self-organized etching technique for fabricating a quasiregular array of MnAs nanoislands

We present a method to fabricate arrays of MnAs islands having diameters of less than 100 nm without using nanofabrication techniques. The strain balance in the MnAs layer grown epitaxially on GaAs substrates collapses when the heterostructure is immersed in a wet-chemical etch solution. As a consequence, the MnAs layer develops a regular row of cracks and submicron-wide strips are carved from it. The strips are additionally sliced into islands during etching since two phases of MnAs, alpha-MnAs and beta-MnAs, which alternate in a periodic way along the strips, are etched at different rates. The period of the quasiregular array of MnAs islands can be adjusted through the thickness of the MnAs layer. We also show that MnAs islands can serve as a nearly ideal etch mask to create GaAs columns by dry etching. (C) 2003 American Institute of Physics.