Effect of heat and plasma treatments on the electrical and optical properties of colloidal indium tin oxide films

ITO;RIE;Indium tin oxide;Colloidal films;Annealing;Plasma treatment;Reactive ion etching;Impedance spectroscopy

Joshi, Salil Mohan ; Gerhardt, Rosario A. Materials Science and Engineering Graham, Samuel Deng, Yulin Lin, Zhiqun Carter, William B. Ivanov, Ilia N. ; Gerhardt, Rosario A.

University:Georgia Institute of Technology

Department:Materials Science and Engineering

关键词: ITO;    RIE;    Indium tin oxide;    Colloidal films;    Annealing;    Plasma treatment;    Reactive ion etching;    Impedance spectroscopy;   

Others  :  https://smartech.gatech.edu/bitstream/1853/52170/1/JOSHI-DISSERTATION-2013.pdf

美国|英语

来源: SMARTech Repository

【 摘 要 】

The research presented in this dissertation explores the possibility of using colloidal indium tin oxide (ITO) nanoparticle solutions to direct write transparent conducting coatings (TCCs), as an alternative route for TCC fabrication. ITO nanoparticles with narrow size distribution of 5-7 nm were synthesized using a non-aqueous synthesis technique, and fabricated into films using spin coating on substrates made from glass and fused quartz. The as-coated films were very transparent (>95% transmittance), but highly resistive, with sheet resistances around 10¹³ Ω/sq . Pre-annealing plasma treatments were investigated in order to improve the electrical properties while avoiding high temperature treatments. Composite RIE treatment recipes consisting of alternating RIE treatments in O₂ plasma and in Ar plasma were able to reduce the sheet resistance of as spin coated ITO films by 4-5 orders of magnitude, from about 10¹³ Ω/sq in as-coated films to about 3 x 10⁸ Ω/sq without any annealing. Plasma treatment, in combination with annealing treatments were able to decrease the sheet resistance by 8-9 orders of magnitude down to almost 10 kΩ/sq , equivalent to bulk resistivity of ~0.67 Ω.cm. Investigation into effectiveness of various RIE parameters in removing residual organics and in reducing the sheet resistance of colloidal ITO films suggested that while reactive ion annealing (RIE) pressure is an important parameter; parameters like plasma power, number of alternating O₂-Ar RIE cycles were also effective in reducing the residual organic content. Impedance spectroscopy analysis of the colloidal ITO films indicated the dominance of the various interfaces, such as grain boundaries, insulating secondary phases, charge traps, and others in determining the observed electrical properties.