Deep‐Ultraviolet Luminescence Properties of AlN

High‐resolution, low‐excitation photoluminescence (PL) spectroscopy is performed for unintentionally doped, silicon‐doped, and magnesium‐doped homoepitaxial aluminum nitride (AlN) films, using a wavelength‐tunable high‐repetition‐rate laser. The wavelength‐tunable laser is used to distinguish between the luminescence and scattering signals from AlN. Providing the high‐resolution, low‐excitation PL spectra, the current understanding of the deep‐ultraviolet luminescence properties of AlN is reviewed and potential assignments for the unknown luminescence lines and bands are discussed. Although previous studies have led to a consensus on the origins of some emission peaks and bands such as the neutral silicon donor‐bound exciton transition and free exciton transitions involving longitudinal optical phonons, it is shown that many of the emission peaks are still unidentified. The origins of all the emission peaks should be elucidated to enable control of the electronic and optoelectronic properties of AlN.