基于有机硅栅绝缘层的制备工艺对OTFT性能的影响

Effects of Fabrication Process of Organo-Silicon Based Organic Gate Insulators on Performance of Organic Thin-Film Transistors

摘要:

基于聚合物绝缘材料和半导体材料, 采用溶液法旋涂工艺制作了有机薄膜晶体管(OTFT), 通过尝试不同旋涂速度、表面预处理、退火温度等条件来优化聚合物绝缘材料的制备工艺参数, 获得了良好的绝缘性的聚合物绝缘材料和器件特性。结果表明, 绝缘层旋涂速度过快、表面用氧等离子体处理时间过长和退火温度过低都会降低有机栅极绝缘层(OGI )的绝缘性和OTFT的器件特性。采用硅氧烷材料作为聚合物栅极绝缘层, 其溶液由硅氧烷单体和溶剂加丙二醇甲醚醋酸酯(PGMEA)混合而成。OGI的旋涂速度为1200r/min, 退火温度为140℃, 在旋涂有机半导体材料之前, 需在退火之后的硅氧烷表面进行短暂的氧离子灰化反应。得到的有机薄膜晶体管迁移率约为0.4cm²·V^-1·s^-1, 亚阈值摆幅降至约1.2V/dec, 开关比大于10⁴, 并且当外加电场为1MV/cm时, 漏电流密度低于1.4×10^-6A/cm²(V_ds=-40V)。

Abstract:

Based on polymeric insulators and semiconductors, solution processed organic thin-film transistors (OTFTs) are investigated. It has been tried to improve dielectric properties and performance of OTFT devices by optimizing fabrication process, such as using different OGI spin-coating rates, surface treatment time and annealing temperature. The results show high spin-coating rate, long surface treatment time and low annealing temperature will decrease dielectric properties and device performance of OTFT. An organo-silicon-based polymer, namely siloxane, is used as a polymeric gate insulating layer. In this study, the OGI solution formulation is simply composed of the siloxane monomer and the solvent, propylene glycol monomethyl acetate (PGMEA). The spin-coated siloxane film was further annealed at 140℃. A quick oxygen reactive ion ashing was applied to the annealed siloxane surface prior to spin-coating the organic semiconductor layer. The OTFT exhibits a decent mobility up to ~0.4cm²·V^-1·s^-1, sub-threshold swing down to ~1.2V/dec, on-off ratio higher than 10⁴ and gate leakage density less than ~1.4×10^-6A/cm²(V_dsunder an applied electric field of ~1MV/cm (V_ds=-40V).