High-aspect ratio patterning of MnAs films

We report the high-aspect ratio patterning of epitaxial MnAs-on-GaAs(0 0 1) films. The control of strain is key since MnAs-on-GaAs(0 0 1) exhibits a strain-stabilized coexistence of two chemically, elastically and magnetically distinct phases forming a self-organized stripe structure over a temperature range of 10-40 °C. Anisotropic plasma etching allows for high-aspect ratios and good reproducibility. Using Ti films as an etch mask, arbitrarily oriented structures can be transferred into films of up to 300 nm thickness. The removal of the masking material is challenging as MnAs reacts with all common acids, alkalis and even water. Optimum results are obtained by etching the Ti mask in hydrofluoric acid at elevated temperatures (>50 °C), where MnAs is entirely in its β-phase. © 2006 IOP Publishing Ltd