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Title: Thickness-dependent blue shift in the excitonic peak of conformally grown ZnO:Al on ion-beam fabricated self-organized Si ripples

Al-doped ZnO (AZO) thin films of thicknesses 5,10, 15, 20, and 30 nm were deposited on 500 eV argon ion-beam fabricated nanoscale self-organized rippled-Si substrates at room temperature and are compared with similar films deposited on pristine-Si substrates (without ripples). It is observed that morphology of self-organized AZO films is driven by the underlying substrate morphology. For instance, for pristine-Si substrates, a granular morphology evolves for all AZO films. On the other hand, for rippled-Si substrates, morphologies having chain-like arrangement (anisotropic in nature) are observed up to a thickness of 20 nm, while a granular morphology evolves (isotropic in nature) for 30 nm-thick film. Photoluminescence studies reveal that excitonic peaks corresponding to 5–15 nm-thick AZO films, grown on rippled-Si templates, show a blue shift of 8 nm and 3 nm, respectively, whereas the peak shift is negligible for 20-nm thick film (with respect to their pristine counter parts). The observed blue shifts are substantiated by diffuse reflectance study and attributed to quantum confinement effect, associated with the size of the AZO grains and their spatial arrangements driven by the anisotropic morphology of underlying rippled-Si templates. The present findings will be useful for making tunable AZO-based light-emitting devices.
Authors:
; ;  [1] ;  [2] ;  [3] ; ;  [4]
  1. Institute of Physics, Sachivalaya Marg, Bhubaneswar 751 005 (India)
  2. CENIMAT, Faculdade de Ciencias e Tecnologia, Universidade Nova de Lisboa, Caparica 2829 516 (Portugal)
  3. Surface Physics and Material Science Division, Saha Institute of Nuclear Physics, Kolkata 700 064 (India)
  4. Department of Physics, School of Natural Sciences, Shiv Nadar University, Gautam Budh Nagar, Uttar Pradesh 201 314 (India)
Publication Date:
OSTI Identifier:
22489470
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 118; Journal Issue: 10; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ARGON IONS; BEAMS; DOPED MATERIALS; MORPHOLOGY; NANOSTRUCTURES; PEAKS; PHOTOLUMINESCENCE; SUBSTRATES; TEMPERATURE RANGE 0273-0400 K; THICKNESS; THIN FILMS; ZINC OXIDES