4‑inch AlN on Sapphire Epitaxial Wafer (AlN template) is high‑quality undoped aluminum nitride thin‑film epitaxially deposited on C‑plane sapphire substrate. It features wide band‑gap property, excellent deep‑ultraviolet transparency, high thermal conductivity, low dislocation density and epi‑ready ultra‑smooth surface. This wafer serves as an ideal buffer template for subsequent AlGaN and GaN epitaxy. It is widely used for DUV‑LED, ultraviolet laser diodes, RF‑HEMT, SAW filters and nitride‑based semiconductor research projects. Custom‑tailored AlN film thickness, surface roughness and cleaning grade are available on request.