The structural, electrical, and optical properties of undoped ZnO, F-doped ZnO (ZnO:F), and Al-doped ZnO (ZnO:Al) thin filmswith two different thicknesses deposited by atomic layer deposition (ALD)were investigated to evaluate the electromagnetic interference shielding effectiveness (EMI-SE). A diluted fluoride hydroxide was used as a single reactant source for F doping in a ZnOmatrix, and the F doping concentration was about 1 at.% in the ZnO:F films. The fabrication of the ZnO:Al films was followed by the typical ALD method, and the Al doping concentration of about 2 at.% was adjusted by the dopant deposition intervals of the ZnO:Al2O3 precursor pulse cycle ratios, which were fixed at 19:1. The film thickness variations were controlled with 600 and 1600 total ALD cycles of approximately 100 nmand 300 nm, respectively. The carrier concentration of the films ismonotonically increased in order of the undoped ZnO, ZnO:F, and ZnO:Al films. The EMI-SE values of the undoped ZnO, ZnO:F, and ZnO:Al films at 1 GHz were 0.9 dB, 2.6 dB, and 6.0 dB for ∼100 nm, and were 2.1 dB, 9.7 dB, and 13.1 dB for ∼300 nm, respectively. In our work, the EMI-SE value was increased by the enhancement of both the carrier concentration and film thickness due to reflection via the free carrier scattering effect.
Bibliographical noteFunding Information:
This work was supported by the Industrial Strategic Technology Development Program ( 10041926 , development of high density plasma technologies for thin film deposition of nanoscale semiconductor and flexible display processing) funded by the Ministry of Knowledge Economy (MKE, Korea). This work was supported by the third stage of the Brain Korea 21 Plus Project in 2014.
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All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Surfaces and Interfaces
- Surfaces, Coatings and Films
- Metals and Alloys
- Materials Chemistry