Shadow modulated two-dimensional heterostructures using vertical pillars

A vertical pillar shadow epitaxy technique is introduced for fabricating coplanar striped or cross-hatched GaAsAlAs two-dimensional heterostructures, where the pattern area of each individual layer can be varied in situ. An array of vertical pillars is mounted adjacent to the substrate wafer to block epitaxial molecular flux, with shadow position determined by the azimuthal substrate angle, and feature resolution set by source diameter. Complex planar heterostructures can be achieved in a single epitaxial growth, such as the checkerboard of superlattices with varying period number demonstrated here. Superlattice layers are characterized via scanning electron microscope, and thicknesses closely match an umbra/penumbra model. © 2008 American Institute of Physics.