Planarization of epitaxial GaAs overgrowth over tungsten wires

We report on thin GaAs epitaxial overgrowth over tungsten wires. The aim of the study is to overgrow the grating without the formation of voids above the tungsten wires and to investigate the planarization of the growth front over the grating. It is established that the most important factors for rapid planarization of the overgrowth for given epitaxial conditions are the crystallographic orientation of the grating, the grating period, and the ratio of the growth rates for the different facets formed in the growth front. For a 300 nm period grating and a metal width of 100 nm, a planarized growth front is demonstrated after 200 nm of growth.