Strain modification of AlGaN layers using swift heavy ions

Epitaxial AlGaN/GaN layers grown by molecular beam epitaxy (MBE) on SiC substrates were irradiated with 150MeV Ag ions at a fluence of 5 x 10(12) ions/cm(2). The samples used in this study are 50 nm Al(0.2)Ga(0.8)N/1 nm AlN/1 mu m GaN/0.1 mu m AlN grown on SI 4H-SiC. Rutherford backscattering spectrometry/channeling strain measurements were carried out on off-normal axis of irradiated and unirradiated samples. In an 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 dechanneling 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, the defect density increased on both GaN and AlGaN layers. The effect of irradiation induced-damages are analyzed as a function of material properties. Observed results from different characterization techniques such as RBS/channeling, high-resolution XRD and AFM are compared and complemented with each other to deduce the information. Possible mechanisms responsible for the observations have been discussed in detail.