to be the z direction has quantum confinement because the feature size i e the layer thickness is very small however there is no confinement in the plane of growth which is the x y plane a single crystal germanium crystal is grown on top of the algaas gaas superlattice by epitaxial deposition at 400 u00b0 c this can be done because the lattice constant of the germanium is almost the same as that of the algaas and gaas a thin film of gold is epitaxially deposited on top of the germanium at 100 u00b0 c a layer of a photoresist composition is formed on top of the gold surface using a mask an image is transferred to the photoresist to provide a pattern which is a very narrow slit parallel to the x direction the gold and germanium layers that are exposed after the photoresist has been developed are etched away encapsulate the thusly formed wafer in silicon nitride and anneal at 340 u00b0 c to attain essentially homogeneous solid phase compositional disordering in the uppermost region of the algaas gaas superlattice beneath the regions covered by the patterned gold germanium layers the algaas gaas superlattice below the germanium and gold homogenizes because the in diffusion of gold and germanium enhances the out diffusion of the gallium there is little interdiffusion below the region where there are no germanium and gold layers thus the patterned slit is reproduced as a superlattice that is a line parallel to the x direction there is now confinement in the y direction by the homogenized material that was a.