Effects of Ambience on Thermal-Diffusion Type Ga-doping Process for ZnO Nanoparticles

• Published in: Coatings (Basel) Vol. 12; no. 1; p. 57
• Main Authors: Islam, Md Maruful, Yoshida, Toshiyuki, Fujita, Yasuhisa
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 04.01.2022
• Subjects: Ambience; Atmospheres; Atmospheric effects; Chemical vapor deposition; Crystallites; Diffraction patterns; Doping; Doppler effect; Electric arcs; Electric fields; Electrical properties; Electrical resistivity; Electrodes; Gallium; Glass substrates; Microscopy; Morphology; Nanomaterials; Nanoparticles; Optical properties; Red shift; Semiconductor devices; Thermal diffusion; Thin films; Transistors; Wurtzite; Zinc oxide; United States > US; Japan
• ISSN: 2079-6412; 2079-6412
• DOI: 10.3390/coatings12010057

Various annealing atmospheres were employed during our unique thermal-diffusion type Ga-doping process to investigate the surface, structural, optical, and electrical properties of Ga-doped zinc oxide (ZnO) nanoparticle (NP) layers. ZnO NPs were synthesized using an arc-discharge-mediated gas evaporation method, followed by Ga-doping under open-air, N2, O2, wet, and dry air atmospheric conditions at 800 °C to obtain the low resistive spray-coated NP layers. The I–V results revealed that the Ga-doped ZnO NP layer successfully reduced the sheet resistance in the open air (8.0 × 102 Ω/sq) and wet air atmosphere (8.8 × 102 Ω/sq) compared with un-doped ZnO (4.6 × 106 Ω/sq). Humidity plays a key role in the successful improvement of sheet resistance during Ga-doping. X-ray diffraction patterns demonstrated hexagonal wurtzite structures with increased crystallite sizes of 103 nm and 88 nm after doping in open air and wet air atmospheres, respectively. The red-shift of UV intensity indicates successful Ga-doping, and the atmospheric effects were confirmed through the analysis of the defect spectrum. Improved electrical conductivity was also confirmed using the thin-film-transistor-based structure. The current controllability by applying the gate electric-field was also confirmed, indicating the possibility of transistor channel application using the obtained ZnO NP layers.