Heteroepitaxy of Highly Oriented GaN Films on Non‐Single Crystal Substrates Using a Si(111) Template Layer Formed by Aluminum‐Induced Crystallization (Phys. Status Solidi RRL 3/2018)

Abstract

For most light-emitting diodes (LEDs), high power electronics and solar cells applications, gallium nitride must be deposited as a thin film on the surface of another single-crystal material. By using the periodic arrangement of surface atoms as a template, gallium and nitrogen atoms can arrange themselves to form a crystalline thin film. For LED applications in particular, silicon carbide and sapphire are the most widely used single crystal substrates because they are transparent and their atomic arrangement is symmetrically matched with that of gallium nitride. While glass is cheaper than these substrates and also transparent, it lacks a regular, uniform arrangement of its atoms. This lack of a surface template pattern means that the Ga and N atoms have no template, so GaN cannot be grown directly on its surface. In article no. 1700392, this problem is overcome by forming an ultrathin (∼30 nm) silicon layer on the glass surface. The ultrathin silicon film provides a uniformly oriented surface that acts as the template for GaN growth, while being thin enough to remain transparent. This work also demonstrates that other amorphous and mismatched substrates, such as oxidized Si(001) and polycrystalline diamond, can be used in the same manner.