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Structural and Electrical Characterization of ZnO Films Grown by Spray Pyrolysis and Their Application in Thin‐Film Transistors
Author(s) -
Adamopoulos George,
Bashir Aneeqa,
Gillin William P.,
Georgakopoulos Stamatis,
Shkunov Maxim,
Baklar Mohamed A.,
Stingelin Natalie,
Bradley Donal D. C.,
Anthopoulos Thomas D.
Publication year - 2011
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201001089
Subject(s) - materials science , thin film , fourier transform infrared spectroscopy , crystallite , analytical chemistry (journal) , substrate (aquarium) , photoluminescence , spectroscopy , chemical engineering , optoelectronics , nanotechnology , organic chemistry , chemistry , oceanography , physics , quantum mechanics , geology , engineering , metallurgy
The role of the substrate temperature on the structural, optical, and electronic properties of ZnO thin films deposited by spray pyrolysis using a zinc acetate precursor solution is reported. Analysis of the precursor compound using thermogravimentry and differential scanning calorimetry indicates complete decomposition of the precursor at around 350 °C. Film characterization using Fourier Transform Infrared Spectroscopy (FTIR), photoluminescence spectroscopy (PL), and ultraviolet–visible (UV–Vis) optical transmission spectroscopy suggests the onset of ZnO growth at temperatures as low as 100 °C as well as the transformation to a polycrystalline phase at deposition temperatures >200 °C. Atomic force microscopy (AFM) and X‐ray diffraction (XRD) reveal that as‐deposited films exhibit low surface roughness (rms ≈ 2.9 nm at 500 °C) and a crystal size that is monotonously increasing from 8 to 32 nm for deposition temperatures in the range of 200–500 °C. The latter appears to have a direct impact on the field‐effect electron mobility, which is found to increase with increasing ZnO crystal size. The maximum mobility and current on/off ratio is obtained from thin‐film transistors fabricated using ZnO films deposited at >400 °C yielding values on the order of 25 cm 2 V −1 s −1 and 10 6 , respectively.