Regulation of Substrate-Target Distance on the Microstructural, Optical and Electrical Properties of CdTe Films by Magnetron Sputtering

oleh: Peng Gu, Xinghua Zhu, Haihua Wu, Dingyu Yang

Format: Article
Diterbitkan: MDPI AG 2018-12-01

Deskripsi

Cadmium telluride (CdTe) films were deposited on glass substrates by direct current (DC) magnetron sputtering, and the effect of substrate-target distance (<i>D<sub>ts</sub></i>) on properties of the CdTe films was investigated by observations of X-ray diffraction (XRD) patterns, atomic force microscopy (AFM), UV-VIS spectra, optical microscopy, and the Hall-effect measurement system. XRD analysis indicated that all samples exhibited a preferred orientation along the (111) plane, corresponding to the zinc blende structure, and films prepared using <i>D<sub>ts</sub></i> of 4 cm demonstrated better crystallinity than the others. AFM studies revealed that surface morphologies of the CdTe films were strongly dependent on <i>D<sub>ts</sub></i>, and revealed a large average grain size of 35.25 nm and a high root mean square (RMS) roughness value of 9.66 nm for films fabricated using <i>D<sub>ts</sub></i> of 4 cm. UV-VIS spectra suggested the energy band gap (<i>Eg</i>) initially decreased from 1.5 to 1.45 eV, then increased to 1.68 eV as <i>D<sub>ts</sub></i> increased from 3.5 to 5 cm. The Hall-effect measurement system revealed that CdTe films prepared with a <i>D<sub>ts</sub></i> of 4 cm exhibited optimal electrical properties, and the resistivity, carrier mobility, and carrier concentration were determined to be 2.3 &#215; 10<sup>5</sup> Ω∙cm, 6.41 cm<sup>2</sup>∙V<sup>&#8722;1</sup>∙S<sup>&#8722;1</sup>, and 4.22 &#215; 10<sup>12</sup> cm<sup>&#8722;3</sup>, respectively.