A type of shadow mask growth technique (cantilever shadow masking) for reduced area molecular beam epitaxial growth has been developed and applied to the growth of GaAs and InxGa1−xAs on selective areas of Si and GaAs substrates, respectively. This technique eliminates detrimental sidewall growth interactions, results in precisely positioned growth areas, and can be more readily planarized than other reduced area growth structures. This technique is particularly useful for defect density reduction during latticed‐mismatched heteroepitaxy using reduced growth areas.