Ellipsometric Investigation of Optical Parameters and Characterization of Spray Pyrolysis-Derived ZnO Films
- PDF / 1,637,672 Bytes
- 8 Pages / 593.972 x 792 pts Page_size
- 73 Downloads / 203 Views
uctive oxide (TCO) materials occupy an important part in the domain of the microelectronic and the optoelectronics.[1–3] Zinc oxide (ZnO) is one of the most important members of Transparent Conductive Oxide (TCO) materials.[4–7] ZnO has attracted a great deal of attention due to their potential applications in microelectronics and optoelectronics.[8–11] It can be used in a large number of areas, and unlike many of the materials with which it competes, ZnO is inexpensive, relatively abundant, chemically stable, easy to prepare, and nontoxic. As an interesting chemically and thermally stable ntype semiconductor, ZnO has a large exciton binding energy of 60 meV and wide band gap energy of 3.37 eV at room temperature. The non-stoichiometric ZnO thin films usually exhibit n-type behavior with low resistivity due to the oxygen vacancies and zinc interstitials. Transparent conducting oxide (TCO) technology needs new and alternative materials with improved characteristics. ZnO films have been synthesized by using different techniques which include electrodeposition,[12] thermal evaporation,[13] chemical bath deposition,[14] dc magnetron sput-
tering,[15] spray pyrolysis,[16] sol–gel,[17] and pulsed laser deposition.[18] Among them, use of a low-cost technique is also important for cost-reduction purposes. For this reason, we have used an ultrasonic spray pyrolysis (USP) set-up which is simple and economic; allow doping of different elements; and deposition onto large-areas without the need for vacuum. There are many works on structural, optical, surface, and electrical ZnO films.[19–26] Also, spectroscopic ellipsometry technique has been recently used to investigate the optical parameters of ZnO films.[27– 32] But, there is no report on the effect of low pH value on some optical parameters such as refractive indices and extinction coefficient values of ZnO films by spectroscopic ellipsometry. So, we focused on the effect of pH on the ellipsometric investigation of ZnO films. With respect to this, we have produced ZnO films by spray pyrolysis at five different pH values and the effect of pH values of solution on the structural, optical, surface, and electrical properties of ZnO films have been investigated by spectroscopic ellipsometry and suitable analysis techniques.
II. OLCAY GENC¸YILMAZ, is with the Department of Physics, Faculty of Science, C¸ankırı Karatekin University, 18100 C¸ankırı, Turkey, Contact e-mails: [email protected], eren_o@ _ _ AKYU¨Z, Professors, hotmail.com FERHUNDE ATAY and IDR IS are with the Department of Physics, Faculty of Arts and Science, Eskis¸ehir Osmangazi University, 26480 Eskis¸ehir, Turkey. Manuscript submitted October 9, 2014. Article published online June 24, 2015 METALLURGICAL AND MATERIALS TRANSACTIONS A
EXPERIMENTAL DETAIL
A. Film Formation ZnO films were produced using spray pyrolysis at five different pH values from 6.9 to 3.2. The ultrasonic oscillator frequency was 100 kHz, and the droplet size was 20 lm. Heated microscope glasses (Objekttrager, 1 cm 9 1 cm) were used as substrate. Substr
Data Loading...
