Intense orange emission from hydrothermally synthesized ZnO flower-like structure: effect of charge carrier—LO phonon interaction on emission characteristics

• Published in: Applied physics. A, Materials science & processing Materials science & processing, 2021-03, Vol.127 (3), Article 163
• Main Authors: Raha, Joyeta, Haldar, Nibedita, Ghosh, Chandan Kumar
• Format: Article
• Language: English
• Subjects: Applied physics; Characterization and Evaluation of Materials; Condensed Matter Physics; Current carriers; Defects; Emissions control; Machines; Manufacturing; Materials science; Nanotechnology; Optical and Electronic Materials; Optical properties; Optoelectronics; Parameters; Phonons; Photoluminescence; Physics; Physics and Astronomy; Processes; Raman spectroscopy; Surfaces and Interfaces; Synthesis; Thin Films; Zinc oxide
• ISSN: 0947-8396; 1432-0630
• DOI: 10.1007/s00339-021-04281-7

Easy control of electronic and optical properties of ZnO is pivotal for its various optoelectronic applications. The present manuscript illustrates preparation of flower- and needle-like microstructures of ZnO by simple hydrothermal technique using Zn(NO 3 ) 2 and NaOH as precursors. The method is found to be suitable to generate different ZnO microstructures just by changing NaOH concentration. Other parameters such as reaction temperature, time have no significant effect other than change of size of the microstructures. After careful analyses of the microstructures by Raman spectroscopy, it appears that charge carrier—LO phonon interaction which plays important role in optoelectronic properties decreases with increasing NaOH concentration. Photoluminescence spectroscopic data depict that the synthesized microstructures exhibit intense and tunable orange emission at 620 nm, attributed to interstitial oxygen defects. The present protocol is found to be very effective to control defects of ZnO microstructures; particularly, it seems to be very sensitive to control oxygen interstitial. Full width at half maxima (FWHM), an important parameter of any optical emission, is observed to be decreasing with increasing NaOH. A theoretical model, developed on the basis of Huang—Rhys ‘S’ factor, has been developed to correlate the trend of FWHM considering charge carrier—LO phonon interaction and orbital radii of the charge carriers.