Control of the formation of self-assembled nano-voids at the GaN/GaAs interface

The self-assembling of nanovoids with a precisely controlled depth at the GaN/GaAs interface is reported and their formation mechanism discussed. During the very early stages of GaN growth by molecular beam epitaxy over GaAs(100) misoriented substrates, nano-pits are formed by chemical reactions of gallium and nitrogen with a GaAs sacrificial layer. The GaAs sacrificial layer is grown on top of a GaAs/AlGaAs superlattice that is used to efficiently stop the in-depth etch and to promote lateral etching. Thus, a nanostructure of wide voids and pedestals is self-assembled and confined at the interface. As an application, the lift-off of GaN epilayers from the substrate was carried out successfully, a fact that opens up the applicability of this process in other semiconductor systems.