Combinatorial Pulsed Laser Deposition of ITO-ZnO:Al Thin Films for Solar Cells Applications
- PDF / 216,901 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 65 Downloads / 214 Views
1074-I05-05
Combinatorial Pulsed Laser Deposition of ITO-ZnO:Al Thin Films for Solar Cells Applications Doina Craciun1, Gabriel Socol1, Ion N. Mihailescu1, and Valentin Craciun1,2 1 National Institute for Laser, Plasma and Radiation Physics, Bucharest, 077125, Romania 2 MAIC, University of Florida, Gainesville, FL, 32611 ABSTRACT Transparent and conductive mixtures of ITO-ZnO and ITO-ZnO:Al have been deposited by a combinatorial pulsed laser deposition on Si and quartz substrates. Measurements of the In to Zn ratios along the transversal axis of the substrates were performed using energy dispersive x-ray spectroscopy. From simulations of the x-ray reflectivity spectra, collected with a 2 mm mask on different locations along the transversal axis of the samples, the density and thickness of the deposited films were calculated and then the In to Zn ratios. The crystalline structure and electrical properties of the deposited films were also investigated along the same axis. Changes in the ratio of In/Zn along this axis resulted in changes of the lattice constant, texture, optical and electrical properties of the films. By changing the In to Zn ration we could tailor the properties of the transparent electrode and find ways to partially replace the more expensive ITO material with ZnO.
INTRODUCTION The top transparent electrode is a key element of a solar cell, controlling the amount of light that is captured and protecting it from ambient interactions. So far, ITO is the most used material for transparent and conducting electrodes [1, 2]. Unfortunately, In is rather expensive and scarce, which will limit its application in a large scale industrial production of solar cells. There were various studies and investigation aiming at replacing or mixing ITO with inexpensive and abundant ZnO:Al [3-5]. Mixing of various materials to obtain new and better properties or functionalities are wellknown processes employed to meet the challenges of demanding applications. Since it is not yet possible to predict, based on first principles, the right amount of doping or alloying element to optimize a specific property of the new phase or material studied, various strategies have been developed. The combinatorial method, where two or more sources of atomized materials are simultaneously or alternatively used for deposition on a single substrate is a very good example of successful optimization work [6-8]. We have used the combinatorial pulsed laser deposition (CPLD) method to obtain transparent and conductive oxides by mixing indium tin oxide (ITO) with pure or aluminum doped zinc oxide (ZOA). By mixing these two components we also wanted to tailor the mechanical, crystalline and optical properties of these transparent and conductive films.
EXPERIMENT Targets of ITO and ZnO (or ZnO:Al), located in two different positions, were ablated sequentially using a KrF laser. The material was collected on Si or quartz substrates heated from 300 up to 500 oC. Films grown separately from each target will have their maximum thickness positioned a
Data Loading...
