Structural Changes Induced by Swift Heavy Ion Beams in tensile strained Al (1-x) In x N /GaN Hetero-structures
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Structural Changes Induced by Swift Heavy Ion Beams in tensile strained Al (1-x)InxN /GaN Hetero-structures G. Devaraju, Anand P. Pathak, N. Srinivasa Rao, V. Saikiran, N. Sathish and S. V.S Nageswara Rao School of Physics, University of Hyderabad, Hyderabad 500046, A P, India ABSTRACT We report here swift heavy ion (SHI) irradiation induced effects on structural and surface properties of III-nitrides. Tensile strained Al(1-x)InxN/GaN Hetero-Structures (HS) were realized using Metal Organic Chemical Vapour Despotion (MOCVD) technique with indium composition as 12%. Ion species and energies are chosen such that electronic energy deposition rates differ significantly in Al(1-x)InxN and are essential for understanding the ion beam interactions at the interfaces. Thus the samples were irradiated with 80 MeV Ni6+ and 100 MeV Ag7+ ions at varied fluence (1×1012 and 3 ×1012 ions/cm2) to alter the structural properties. Under this energy regime, the structural changes in Al(1-x)InxN would occur due to the intense ultrafast excitations of electrons along the ion path. We employed different characterization techniques like High Resolution X- ray Diffraction (HRXRD) and Rutherford back scattering spectrometry (RBS) for composition, thickness and strain. HRXRD and RBS experimental spectra have been fitted with Philip’s epitaxy SIMNRA code, which yields thickness and composition from compound semiconductors. The surface morphology of pristine and irradiated samples is studied and compared by Atomic Force Microscopy (AFM). INTRODUCTION III-Nitride compound semiconductors have tremendous applications in opto-electronic, high frequency and high power devices. In spite of huge defect densities [1] (four orders of magnitude higher than those in their counterpart compounds based on GaAs), these materials show excellent luminescence and electrical properties. Among family of nitrides, the Al(1íx) InxN alloys are much less investigated than InxGa(1íx)N and AlxGa(1íx)N because it is very difficult to obtain high-quality Al(1íx) InxN layers due to significant difference of thermal stability between InN and AlN [2–4]. However, Al(1íx) InxN is a promising candidate in Bragg reflectors and field effect transistors[5-6]. Due to their technological importance in satellite communications, there is a need to understand how device performance degrades under radiation treatment of these semiconductor materials. Much has not been explored but it is observed that high-energy ions create carrier traps which compromise electrical and optical properties [7, 8]. Hence there is great demand to understand the interfaces of these HS, their strain and surface morphology under the effects of heavy ion irradiation. In this work, the Al(1íx)InxN Hetero-Structures (HS) were grown on sapphire with GaN templates on c plane sapphire. These structures were irradiated with Ni and Ag ions.
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Subsequently, the surface morphology was studied by Atomic Force Microscopy (AFM). It is found that ion irradiation can obviously influence the surface morphology. The (0002
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