Band gap engineering of nano scale AlGaN epitaxial layers by swift heavy ion irradiation

Epitaxial AlGaN/GaN layers grown by MBE on SiC substrates were irradiated with 150 MeV Ag ions at a fluence of 5×1012 ions/cm 2. AlGaN/GaN Multi Quantum Wells (MQWs) were grown on Sapphire substrate by Metal Organic Chemical Vapour Deposition (MOCVD) and irradiated with 200 MeV Au8+ ions at a fluence of 5×1011 ions/cm2. These samples were used to study the effects of Swift Heavy Ions (SHI) on optical properties of AlGaN/GaN based nano structures. Rutherford Back Scattering (RBS) /Channelling measurements were carried out at off normal axis on irradiated and unirradiated samples to extract strain. In as grown samples, AlGaN layer is partially relaxed with a small compressive strain. After irradiation this compressive strain increases by 0.22% in AlGaN layer. Incident ion energy dependence of dechannelling parameter shows E1/2 dependence, which corresponds to the dislocations. Defect densities were calculated from the E1/2 graph. As a result of irradiation defect density increased on both GaN and AlGaN layer. Optical properties of AlGaN/GaN MQWs before and after irradiation have been analyzed using PL. In this study, we present some new results concerning high-energy irradiation on AlGaN/GaN heterostructures and MQWs characterized by RBS/Channelling and Photo Luminescence (PL).