Heteroepitaxy of Highly Oriented GaN Films on Non‐Single Crystal Substrates Using a Si(111) Template Layer Formed by Aluminum‐Induced Crystallization

Growth of epitaxial III‐nitride (AlGaInN) films has long been confined to single crystal substrates which are crystallographically compatible with the hexagonal GaN (0001) surface. However, for lighting, display, and power electronics applications, growth on amorphous substrates such as fused quartz glass or on polycrystalline diamond is desirable. Several approaches to produce c‐plane oriented, textured GaN films on glass have been previously demonstrated, but are process‐intensive and limited in scalability. In this report, we demonstrate the heteroepitaxial growth of textured GaN films on fused quartz and other substrates using thin silicon film templates fabricated by aluminum‐induced crystallization (AIC). The AIC‐Si films have a uniform (>95%) Si (111) oriented surface, enabling well‐developed GaN‐on‐Si epitaxial growth processes to be adapted to new substrates. GaN films grown on fused quartz using metalorganic chemical vapor deposition (MOCVD) have uniformly c‐axis oriented grains, ≈40–50 μm in size, with random in‐plane orientations similar to those of the underlying AIC‐Si template layer. Threading dislocation densities of 8.5 ± 1.8 × 109 cm−2 within regions bounded by grain boundaries are comparable to GaN films grown on single crystal Si (111) substrates. Finally, highly oriented GaN growth on AIC‐Si is also achieved on both oxidized Si (001) substrates and polycrystalline diamond, demonstrating the general applicability of this approach. Uniformly c‐axis oriented gallium nitride on fused quartz substrates is realized through the introduction of an ultrathin (∼30 nm) silicon thin film formed on the substrate surface through aluminum‐induced crystallization. The highly uniform Si(111) surface orientation of the film provides a template for c‐axis oriented GaN growth resulting in textured GaN films with dislocation densities comparable to films grown on single crystal Si(111) substrates.