Preparation and properties of transparent conductive aluminum-doped zinc oxide thin films by sol–gel process

Abstract

Highly conductive and transparent aluminum-doped zinc oxide thin films have been prepared from the solution of zinc acetate and aluminum nitrate in ethanol by the sol–gel process. The effect of changing the aluminum-to-zinc ratio from 0 to 5 at. % and annealing temperature from 0 °C to 700 °C in air has been investigated. The resistivities of thin films were measured as a function of annealing temperature and also as a function of aluminum dopant concentration in the solution. As-deposited films have high resistivity and high optical transmission. Annealing of the as-deposited films in air leads to a substantial reduction in resistivity. The films have a minimum value of resistivity of 1.5×10−4 Ω cm for 0.8 at. % aluminum-doped zinc oxide and a maximum transmission of about 91% when deposited on glass substrates. X-ray diffraction measurements employing Cu Kα radiation were performed to determine the crystallinity of the ZnO:Al films which showed that the films were polycrystalline with a hexagonal structure when annealed at 500 °C.

Comparison of various sol–gel derived metal oxide layers for inverted organic solar cells

“…Conductivity increases from 2.12 Â 10 À 3 to 2.35 Â 10 À 3 S/cm with an increase in the Al concentration from 0.5 to 1.0 at%, and then drops to 2.06 Â 10 À 3 S/cm at 2.0 at%. Such trends are not unusual and are frequently interpreted as a neutralization of the dopant atom [17,[27][28][29][30]33]. The annealing temperature has a much stronger influence on the conductivity due to recrystallization of the films.…”

“…[27]. 2.2 g of Zinc acetate (ZnAc Á 2H 2 O) and 0.016 g (1 at%) of aluminum hydroxide acetate (HOAl(C 2 H 3 O 2 ) 2 ) were mixed together and dissolved in 100 ml of ethanol.…”

A comparative study on structural, optical, photoconductivity properties of In and Al doped ZnO thin films grown onto glass and FTO substrates grown by spray pyrolysis process

“…These differences were also caused by the film thickness [38,39]. We concluded that ZnO had good optical transparency in the visible region [40,19]. The absorption and optical band gap are depicted in Fig.…”

“…ZnO films have been grown by several techniques. These methods are spray pyrolysis, either pneumatic [11] or ultrasonic [12,13], chemical vapour deposition [14][15][16], molecular beam epitaxy [17,18], sol-gel [19], pulsed laser deposition [20], sputtering [21][22][23][24][25], hydrothermal technique [26] and wet chemical process such as chemical vapor deposition (CVD), homogenous precipitation method under solvothermal condition [27][28][29].…”

Nano Size Related Piezoelectric Efficiency in a Large ZnO Thin Film, Potential for Self-Powered Medical Device Application

“…A number of techniques, chemical vapor deposition [16], spraypyrolysis [17], molecular beam epitaxy [18], vacuum arc deposition [19], magnetron sputtering [20][21][22] and pulsed laser deposition (PLD) [23], have been involved in the growth of ZnO thin films. Sol-gel method has emerged as an important growth technique because it enables the surface modification of zinc oxide with selected organic compounds.…”