Effects of proton irradiation on Ho doped AlN thin films are investigated. The irradiation is performed in the dose range of 10(13) to 10(14) ions/cm(2) at room temperature. The effect of proton bombardment is studied through a systematic investigation of the structural properties using Rutherford Backscattering Spectroscopy (RBS), X-ray diffraction (XRD), and X-ray Photoemission Spectroscopy (XPS). The optical properties and the band gap change after irradiation process are studied using Defuse Reflectance Spectroscopy (DRS) technique. The electrical behavior of the material is also investigated after irradiation of A1N:Ho. The results show that high-energy protons cause a band gap change in the material, which can be exploited in developing various applications. (C) 2015 Elsevier B.V. All rights reserved.