Epitaxial growth of GaAs by solid-phase transport

(100) GaAs substrates with an Ag film about 45 nm thick were first annealed at 550°C for 30 min in an Ar-flowing furnace (preannealing). A 110-nm-thick GaAs layer was then deposited on top of the preannealed 〈GaAs〉/Ag samples, followed by an amorphous Ta-Si-N film that was deposited over the GaAs layer to serve as a cap layer to minimize the loss of As during the following annealing process. The completed structures were then annealed again at 550°C for 30 min in flowing Ar. The transport of Ga and As through the Ag layer and an epitaxial growth of GaAs on top of the (100) GaAs substrate are observed by cross-sectional transmission electron microscopy and MeV ⁴He backscattering spectrometry. No GaAs epitaxial growth is observed in samples that are not preannealed. Our results demonstrate that epigrowth through a solid transport medium is possible for a III-V semiconductor as it is for Si and Ge.