| 초록 |
Sol-gel Ga-doped ZnO (GZO) films were post-treated in reactive ion etching (RIE) O2 plasma at various rf powers and process time. Influences of O2 plasma post-treatment were investigated in terms of surface morphological, structural, electrical and optical properties and photocurrent of the GZO films. AFM analysis showed that surface roughness of the GZO films increased with O2 plasma post-treatment process time. X-ray diffraction (XRD) measurements indicated that the grains in the GZO films had a strong (002) preferential orientation. Electrical resistivity of the GZO films was significantly lower than that of the control sample. Carrier concentration of the GZO films was increased about 50 times from 5.89x1017 to 3.08x1019 cm-3 in 30 second O2 plasma exposure at 100 W rf power. Moreover, crystallinity of the GZO films post-treated in O2 plasma was enhanced. It could be explained using the XRD study in which the post-treated GZO films had narrower FWHM and the larger crystallite size after 30 second O2 plasma treatment at 100 W rf power. Meanwhile, the photocurrent of the GZO film post-treated in O2 plasma for 30 second was higher than those of the control sample and 60 second O2 plasma post-treatment sample. Therefore, there was an optimum condition for the O2 plasma exposure. The O2 plasma post-treatment increased oxygen vacancies which enhanced the photocurrent generation in the GZO films. |
