Epitaxial AlGaN/GaN layers grown by MBE on SiC substrates were irradiated with 150 MeV Ag ions at a fluence of 5x10¹² ions/cm². Samples used in this study are 50 nm thick AlGaN on 1 µm GaN layer.  RBS/Channelling strain measurements were carried out along off normal axis of irradiated and unirradiated samples. In as grown sample AlGaN layer is partially relaxed with a small tensile strain. After irradiation this strain increases by 0.22% in AlGaN layer. Incident ion energy dependence of dechannelling parameter shows E^1/2 dependence, which corresponds to the dislocations. Defect densities were calculated from the E^1/2 graph. As a result of irradiation defect density increased on both GaN and AlGaN layer. Contact mode AFM has been carried out to measure the surface morphology. As grown sample surface have hillocks and deep holes, implying that both edge and screw dislocations are present in the sample. Irradiated sample shows similar morphology as unirradiated ones. The effect of irradiation induced-damages are analyzed as a function of material properties. Observed results from different characterization techniques like RBS/Channelling, HRXRD and AFM are compared and complemented with each other to deduce the information. Possible mechanisms responsible for the observations have been discussed in detail.

Anand P Pathak*, School of Physics, University of Hyderabad, India
N Sathish, School of Physics, University of Hyderabad, 
S Dhamodaran, Department of Physics, Indian Institute of Technology Kanpur, Kanpur 208016, India, India
B Sundravel, Indra Gandhi Research Centre for Atomic Research, Kalpakkam,, India
KGM Nair, Indra Gandhi Research Centre for Atomic Research, Kalpakkam, India
SA Khan, Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110 067, India
D K Avasthi, Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110 067, India
M Bazan, Dip. Fisica “G.Galilei”, Università di Padova, via Marzolo 8, 35131 Padova, Italy
E Trave, Dip. Fisica “G.Galilei”, Università di Padova, via Marzolo 8, 35131 Padova, Italy
P Mazzoldi, Dip. Fisica “G.Galilei”, Università di Padova, via Marzolo 8, 35131 Padova, Italy

*presenting author