Effects of doping and rapid thermal processing in Y doped CdO thin films

• Published in: Journal of alloys and compounds 2019-03, Vol.776, p.259-265
• Main Authors: Xie, Mengting, Zhu, Wei, Yu, Kin Man, Zhu, Zishu, Wang, Guanzhong
• Format: Article
• Language: English
• Subjects: Band gap; Cadmium oxide; Conduction bands; Doping; Electrons; Heat; Heat conductivity; Magnetron sputtering; Radio frequency magnetron sputtering; Rapid thermal processing; Temperature effects; Thin films; Transition metal doping; Transparent conducting oxides
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2018.10.288

We have synthesized Yttrium (Y)-doped Cadmium Oxide (YCO) thin films by radio frequency magnetron sputtering with Y doping concentration up to 9%. We find that as-deposited YCO films are polycrystalline in the rock-salt structure with electron concentration increases slightly with Y doping concentration. After rapid thermal processing (RTP), the crystallinity of YCO films are improved, resulting in an increased Y activation up to a free electron concentration of 9 × 1020/cm3 for samples with 9% Y. YCO films with low resistivity of 1.5 × 10−4 Ω cm and high mobility of 122 cm2/V are obtained with 1.4% Y doping after RTP at 500 °C. The drop in mobility and increase in intrinsic band gap with Y concentration can be understood in terms of the anticrossing interaction between localized d-states of Y and extended conduction band states of CdO. •Transmittance of the YCO films in the visible and NIR wavelength region is 75–95%.•YCO films with resistivity ∼1.5 × 10−4 Ω cm and mobility ∼122 cm2/V were obtained.•Anticrossing interaction result in the drop in mobility and increase in Eint.