Influence of post-annealing temperature on double layer ZTO/GZO deposited by magnetron co-sputtering

  • Oh, Sung Hoon (Department of Materials Science and Engineering, Pusan National University) ;
  • Cho, Sang Hyun (Department of Materials Science and Engineering, Pusan National University) ;
  • Jung, Jae Heon (Department of Materials Science and Engineering, Pusan National University) ;
  • Kang, Sae Won (Department of Materials Science and Engineering, Pusan National University) ;
  • Cheong, Woo Seok (Printed Devices Research Team, ETRI) ;
  • Lee, Gun Hwan (Functional Coatings Research Group, Korea Institute of Materials Science (KIMS)) ;
  • Song, Pung Keun (Department of Materials Science and Engineering, Pusan National University)
  • Published : 2012.07.01

Abstract

Ga-doped ZnO (GZO) was a limit of application on the photovoltaic devices such as CIGS, CdTe and DSSC requiring high process temperature, because it's electrical resistivity is unstable above 300 ℃ at atmosphere. Therefore, ZTO (zinc tin oxide) was introduced in order to improve permeability and thermal stability of GZO film. The resistivity of GZO (300 nm) single layer increased remarkably from 1.8 × 10-3Ωcm to 5.5 × 10-1Ωcm, when GZO was post-annealed at 400 ℃ in air atmosphere. In the case of the ZTO (150 nm)/GZO (150 nm) double layer, resistivity showed relatively small change from 3.1 × 10-3Ωcm (RT) to 1.2 × 10-2Ωcm (400 ℃), which showed good agreement with change of carrier density. This result means that ZTO upper layer act as a barrier for oxygen at high temperature. Also ZTO (150 nm)/GZO (150 nm) double layer showed lower WVTR compared to GZO (300 nm) single layer. Because ZTO has lower WVTR compared to GZO, ZTO thin film acts as a barrier by preventing oxygen and water molecules to penetrate on top of GZO thin film.

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