Strain modification of AlGaN layers using swift heavy ions |
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Authors: | N Sathish S Dhamodaran B Sundaravel K GM Nair S A Khan |
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Institution: | 1. School of Physics , University of Hyderabad , Hyderabad, 500 046, India;2. Department of Physics , Indian Institute of Technology Kanpur , Kanpur, 208016, India;3. Indra Gandhi Research Centre for Atomic Research , Kalpakkam, India;4. Inter-University Accelerator Centre , Aruna Asaf Ali Marg, New Delhi, 110 067, India |
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Abstract: | Epitaxial AlGaN/GaN layers grown by molecular beam epitaxy (MBE) on SiC substrates were irradiated with 150 MeV Ag ions at a fluence of 5×1012 ions/cm2. The samples used in this study are 50 nm Al0.2Ga0.8N/1 nm AlN/1 μ m GaN/0.1 μ 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. |
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Keywords: | III-Nitrides RBS/channeling HRXRD and swift heavy ions |
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