| 초록 |
· The effect of ZnO and Ga-doped ZnO ( GZO ) thin films with/without O2 plasma post-treatment in a capacitively coupled plasma system was studied. ZnO and GZO samples were prepared on glass substrates using spin coating method. The thin films were post-treated in O2 plasma. RF power and process pressure were 100 W and 10 Pa, respectively. Process time was 120 s. Plasma-treatment ZnO exhibited the highest (002) orientation and the FWHM of X-ray peak was 0.230°. The highest doping concentration was 5.58 x 1016 cm-3 with 1 at.% of Ga without plasma treatment. Pure ZnO had carrier concentration of only 2.85 x 1015 cm-3. However, when oxygen plasma post-treatment was done on the samples, the pure ZnO had 1.99 x 1019 cm-3 of carrier concentration, which was more than three orders of magnitude increase. The variation trend of the resistivity with increasing Ga-doping concentration was apparently different between two cases. The resistivity of the GZO thin films without oxygen plasma post-treatment decreased from 111.37 Ω·cm at 0 at.% to 12.6 Ω·cm at 1 at.% and increased to 36.66 Ω·cm at 4 at.%. However, the resitivity of O2 plasma post-treated GZO increased slightly from 0.042 at the pure ZnO to 0.32 Ω·cm at 3 at.% Ga-doping concentration, and increased sharply to 2.27 Ω·cm at up to 4 at.%. The electrical conductivity of post-treated GZO thin films can be explained by the clear improvement in the crystallinity of the GZO thin films at lower Ga-doping concentration, which was supported by the results from the XRD measurements. |
