Post-growth thermal oxidation of wurtzite InN thin films into body-center cubic In{sub 2}O{sub 3} for chemical/gas sensing applications
- Institute of Materials Research and Engineering (IMRE), A-STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602 (Singapore)
- School of Electrical and Electronic Engineering, Luminous Center of Excellence for Semiconductor Lighting and Display, Nanyang Technological University, Singapore 639798 (Singapore)
Post-growth thermal oxidations of InN have been studied using high-resolution x-ray diffraction (HRXRD) and secondary ion-mass spectroscopy (SIMS). The InN thin films, having relative high crystal quality, were grown by metal–organic chemical vapor deposition (MOCVD) on c-sapphire substrates using InGaN/GaN buffer layers. HRXRD reveals that oxidation of wurtzite InN into body-center cubic In{sub 2}O{sub 3} occurred at elevated temperatures. A Si{sub 3}N{sub 4} encapsulation improves the crystal quality of In{sub 2}O{sub 3} oxidized by using conventional rapid thermal annealing (RTA) but it results in the presence of undesired metallic indium. Cycle-RTA not only improves the crystal quality but also avoids the byproduct of metallic indium. SIMS depth profile, using contaminate elements as the ‘interface markers,’ provide evidence that the oxidation of InN is dominated by oxygen inward diffusion mechanism. Together with the HRXRD results, we conclude that the crystal quality of the resultant In{sub 2}O{sub 3}/InN heterostructure is mainly controlled by the balance between the speeds of oxygen diffusion and InN thermal dissociation, which can be effectively tuned by cycle-RTA. The obtained In{sub 2}O{sub 3}/InN heterostructures can be fundamental materials for studying high speed chemical/gas sensing devices. - Graphical abstract: Oxidation of h-InN into bcc-In{sub 2}O{sub 3} has been realized at elevated temperatures. A Si{sub 3}N{sub 4} cap improves the crystal quality of In{sub 2}O{sub 3} oxidized by conventional RTA but it results in the presence of undesired metallic indium. Cycle-RTA not only improves the crystal quality but also avoids the byproduct of metallic indium. SIMS depth profiles provide evidence that the oxidation of InN is dominated by oxygen inward diffusion mechanism. The crystal quality of the resultant In{sub 2}O{sub 3}/InN heterostructure is mainly controlled by the balance between the speeds of oxygen diffusion and InN thermal dissociation, which can be effectively tuned by cycle-RTA. - Highlights: • Oxidation of h-InN into bcc-In{sub 2}O{sub 3} has been realized at elevated temperatures. • Si{sub 3}N{sub 4} cap improves In{sub 2}O{sub 3} quality obtained by RTA but results in undesired indium. • Cycle-RTA not only improves the quality but also avoids the byproduct of indium. • The oxidation of InN is dominated by oxygen inward diffusion mechanism. • Cycle-RTA tunes the speeds of oxygen diffusion and InN thermal dissociation.
- OSTI ID:
- 22334249
- Journal Information:
- Journal of Solid State Chemistry, Vol. 214; Conference: 7. international conference on materials for advanced technologies, Singapore (Singapore), 30 Jun - 5 Jul 2013; Other Information: Copyright (c) 2013 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
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