Recently, the application of ZnO thin films as an active channel layer of transparent thin film transistor (TFT) has become of great interest. In this study, we deposited ZnO thin films by atomic layer deposition (ALD) from diethyl Zn (DEZ) as a metal precursor and water as a reactant at growth temperatures between 100 and 250 °C. At typical growth conditions, pure ZnO thin films were obtained without any detectable carbon contamination. For comparison of key film properties including microstructure and chemical and electrical properties, ZnO films were also prepared by rf sputtering at room temperature. The microstructure analyses by X-ray diffraction have shown that both of the ALD and sputtered ZnO thin films have (002) preferred orientation. At low growth temperature Ts ≤ 125 °C, ALD ZnO films have high resistivity (> 10 Ω cm) with small mobility (< 3 cm2/V s), while the ones prepared at higher temperature have lower resistivity (< 0.02 Ω cm) with higher mobility (> 15 cm2/V s). Meanwhile, sputtered ZnO films have much higher resistivity than ALD ZnO at most of the growth conditions studied. Based upon the experimental results, the electrical properties of ZnO thin films depending on the growth conditions for application as an active channel layer of TFT were discussed focusing on the comparisons between ALD and sputtering.
Bibliographical noteFunding Information:
This work was supported by Samsung SDI, POSTECH Core Research Program, Korean Research Foundation Grant funded by the Korean Government(MOEHRD)(KRF-2005-005-J13102), and POSRIP. The authors are deeply thankful to Prof. Wang Chul Zin for help in ellipsometry analysis.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Surfaces and Interfaces
- Surfaces, Coatings and Films
- Metals and Alloys
- Materials Chemistry