Effect of ZnO Buffer Layer on the Bending Durability of ZnO:Ga Films Grown on Flexible Substrates: Investigation of Surface Energy, Electrical, Optical, and Structural Properties

• Published in: IEEE transactions on electron devices 2013-07, Vol.60 (7), p.2324-2330
• Main Authors: WU, Jia-Ling, CHEN, Yu-Cheng, LIN, Han-Yu, CHU, Sheng-Yuan, CHANG, Chia-Chiang, WU, Chin-Jyi, JUANG, Yung-Der
• Format: Article
• Language: English
• Subjects: Applied sciences; Bending durability; Buffer layers; Electronics; Exact sciences and technology; Optical buffering; Optoelectronic devices; Periodic structures; Resistance; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Solar energy; Strain; Substrates; surface energy; Thin films; transparent conductive oxide (TCO); Zinc oxide; ZnO buffer layer; ZnO:Ga (GZO)
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/TED.2013.2259491

ZnO:Ga (GZO) transparent conducting oxide (TCO) films are deposited on flexible polyethersulfone (PES) substrates using the radio frequency sputtering technique. The bending durability of flexible TCOs is improved by inserting 100-nm-thick ZnO buffer layers. The strain of the samples with and without buffer layers arising from bending is studied using X-ray diffraction. After the insertion of 100-nm-thick ZnO buffer layers, the strain of GZO films without ZnO after outward and inward bending for 2000 cycles decreases from 2.063 ×10 -3 and 2.203 × 10 -3 to 1.74 × 10 -3 and 1.966 × 10 -3 , respectively. Such strain variation is caused by the difference in adhesive force at the surface of 100-nm-thick ZnO/PES and PES. The surface energy of PES and 100-nm-thick ZnO/PES bent outwards and inwards for 2000 cycles increased from 34.38 and 30.56 to 36.45 and 36.03 mJ/m 2 , respectively.