Monday, 9 August 2010

Iseng : Saya Pusing Akan Kelanjutannya :(


12 days count down... for making tens sample... for characterizing them... for making poster and writing the paper.... So many thing to do with limited time... Could I? I should.... Believe... I can do it.... Bismillah....

 =================================================================


Transparent Conductive Indium Zinc Tin Oxide Thin Films for Solar Cell Applications

Damisih, Hee Young Lee

School of Materials Science and Engineering, Yeungnam University, Gyeongsan, 712-749, South Korea

Abstract
Indium zinc tin oxide (IZTO) thin films were studied as a possible alternative to indium tin oxide (ITO) films for providing low-cost transparent conducting oxide (TCO) for thin film photovoltaic devices. IZTO films were deposited onto glass or flexible polymer substrates at room temperature. A  dc/rf magnetron co-sputtering system equipped with a ceramic target of the same composition was used to deposit TCO films. Earlier studies showed that the resistivity value of In0.6Zn0.2Sn0.2O1.5 (IZTO20) films  could be lowered to approximately 6×10-4 ohm·cm without sacrificing optical transparency and still maintaining amorphous structure through the optimization of process variables. The growth rate was kept at about 8 nm/min while the oxygen-to-argon pressure ratio varied from 0% to 7.5%. As-deposited films were always amorphous and showed strong oxygen pressure dependence of electrical resistivity and electron concentration values. Influence of forming gas anneal (FGA) at medium temperatures was also studied and proven effective in improving electrical properties. In this study, the chemical composition of the targets and the films varied around the In0.6Zn0.2Sn0.2O1.5 (IZTO20). It was the main objective of this paper to investigate how off-stoichiometry affected TCO characteristics including electrical resistivity and optical transmission. In addition to the composition effect, we have also studied how film properties changed with processing variables. It was concluded that IZTO thin films have shown their potential toward indium-saving TCOs, so that they could be adopted in most applications where currently ITO and IZO thin films are being used. The results are also compared to those obtained for commercial ITO thin films from solar cell application viewpoint. 


. INTRODUCTION

Transparent conducting oxides (TCOs) have been widely employed for many applications such as solar cells, flat panel displays, low emissivity windows, thin films transistors, light emitting diode and semiconductor lasers [1-3]. They have been used in wide range applications because of their well known properties, which are high conductivity and high transparency in the visible wavelength region [4]. Until now, indium tin oxide (ITO) still become a popular choice for TCO materials, due to its low resistivity, high stability and compatibility with fine patterning process [5-6]. Eventhough possibly ITO is the most successful TCO in application, its production cost is very high regarding the limited supply and increasing price of indium. Therefore, transparent conducting oxide that contain a reduced amount or no indium have recently received more attention as substitute material for ITO application [7]. As a result, many kinds of new transparent conducting oxide films are reported; polycrystalline or amorphous thin films that show resistivity in order of 10-4 Ω.cm without being highly toxic are possible candidates for use in transparent electrodes. Here, we suggest indium zinc tin oxide (IZTO) as promising alternative TCO material to substitute high cost of ITO for solar cell application due to its low resistivity, high transparency, chemical stability, smooth surface, high work function and low deposition temperature [3,8,9]. In addition, IZTO solubility increase through co-substitutional of In2O3 by ZnO and SnO2 because of isovalent substitution of a Sn4+ and Zn2+ cation for a pair of In3+ [10].

IZTO thin films can be prepared by various kinds of deposition techniques, such as magnetron sputtering, electron gun evaporation, chemical vapor deposition, and spray hydrolysis [11]. In particular, magnetron sputtering is an enormously reliable technique for thin films deposition and has been used in industry for large scale production. The major advantage of magnetron sputtering technique are that can continuously produce high quality film at lower processing temperature. The thin film properties are closely dependent on the deposition method as well as on the deposition parameter. The experimental condition and substrate characteristics, such as RF power, working pressure, substrate temperature and post deposition annealing significantly affect the microstructure, electrical and optical properties.


 


2 comments:

ArIf said...

Mbak, kalau ada sisa, bawa kaca sama ilmunya ke kampus lagi ya, Mbak.. :)

Idham 다미시 said...

Aku ingin sekali kembali ke kampus kita itu Rif... Membagi ilmu yang aku dapat dari sini... Kira-kira masih ada sedikit tempat gak ya? :)