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Crystal Research and Technology |
Cryst. Res. Technol. 41, 1194 (2006) - Abstract -
Influence of substrate temperature and oxygen/argon flow ratio on the electrical and optical properties of Ga-doped ZnO thin films prepared by rf magnetron sputtering
Sookjoo Kim, Jinho Jeon, Hyoun Woo Kim, Jae Gab Lee*, and Chongmu Lee
Department of Materials Science and Engineering, Inha University, Incheon, 402-751, Korea
*School of Advanced Materials Engeneering, Kukmin University, Seoul 136-702, Korea
| Keywords | Ga-doped ZnO, resistivity, transmittance, gas flow ratio, substrate temperature |
| PACS | 73.61.Ga, 78.66.+m, 81.15.-z |
| DOI | 10.1002/crat.200610748 |
Effects of substrate temperature and atmosphere on the electrical and optical properties of Ga-doped ZnO thin films deposited by rf magnetron sputtering were investigated. The electrical resistivity of Ga-doped ZnO (GZO) films decreases as the substrate temperature increases from room temperature to 300°C. A minimum resistivity of 3.3 x 10-4 Ù cm is obtained at 300°C and then the resistivity increases with a further increase in the substrate temperature to 400°C. This change in resistivity with the substrate temperature is related to the crystallinity of the GZO film. The resistivity nearly does not change with the O2/Ar flow ratio, R for R < 0.25 but increases rapidly with R for R > 0.25. This change in resistivity with R is also related to crystallinity. The crystallinity is enhanced as R increases, but if the oxygen partial pressure is higher than a certain level (R = 0.25 ± 0.10) gallium oxides precipitate at grain boundaries, which decrease both carrier concentration and mobility. Optical transmittance increases as R increases for R < 0.75. This change in transmittance with R is related to changes in oxygen vacancy concentration and surface roughness with R.
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