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Solid State Conversion: Microstructuring of Crystalline Al2O3 (Sapphire) by Annealing of Patterned Aluminium Films

Surface structuring on the nano/micro level is important for a huge range of areas. A critical bottle neck for many industrial applications is upscaling; that is to say it must be possible to do the structuring in a comparatively simple and inexpensive manner. However, this is a challenge for many industrially important materials, including sapphire. A few years ago, solid state conversion was introduced as a relatively simply nanoscale structuring method for sapphire. Here we show that the method, by careful choice of parameters, can be extended to work also on the micron scale. We show that a microstructured aluminium film deposited on a Al2O3 (0001) surface is converted into a crystalline Al2O3 surface, when thermally annealed in air, using optimized parameters.