Lee Wen-Hsi, Wang Chun Chieh, Liu Sao-De
Department of Electrical Engineering, National Cheng Kung University, Tainan 70101, Taiwan.
J Nanosci Nanotechnol. 2011 Mar;11(3):1968-75. doi: 10.1166/jnn.2011.3118.
To solve the large leakage current of the heavily blended nanocomposite (Polyimide and nano-TiO2 particles) gate dielectric film exhibiting a high-kappa, the chemical-mechanical polishing (CMP) was adopted to flatten the surface of the PI-TiO2 nanocomposite film. An extremely high dielectric constant (is congruent to 13) of the nanocomposite with CMP treatment is obtained and its leakage current is comparable to that of the neat polyimide in our studies. An OTFT based on the nanocomposite gate dielectric exhibiting high capacitance and a smooth surface after CMP treatment shows very promising performance. Compared with the OTFT based on the neat polyimide gate dielectric, the threshold voltage is improved from -22 to -5 (V), the sub-threshold voltage is decreased from 3.44 to 0.50 (V/dec), the current on/off ratio is increased from 1.6 x 10(6) to 3.53 x 10(8), and the mobility is increased from 0.416 to 0.624 (cm2V(-1)s(-1)). Moreover, it is worth noting that the hysteresis effect of OTFT based the nanocomposite can be significantly reduced due to the few charge trapped in the interface when the nanocomposite dielectric surface was further polished by CMP treatment.
为了解决具有高介电常数的高度混合纳米复合材料（聚酰亚胺和纳米二氧化钛颗粒）栅极介电膜的大泄漏电流问题，采用化学机械抛光（CMP）来平整PI-TiO₂纳米复合膜的表面。经过CMP处理的纳米复合材料获得了极高的介电常数（约为13），并且在我们的研究中其泄漏电流与纯聚酰亚胺相当。基于经过CMP处理后具有高电容和平滑表面的纳米复合栅极介电材料的有机薄膜晶体管（OTFT）显示出非常有前景的性能。与基于纯聚酰亚胺栅极介电材料的OTFT相比，阈值电压从-22提高到-5（V），亚阈值电压从3.44降低到0.50（V/dec），电流开/关比从1.6×10⁶增加到3.53×10⁸，迁移率从0.416增加到0.624（cm²V⁻¹s⁻¹）。此外，值得注意的是，当通过CMP处理进一步抛光纳米复合介电表面时，基于纳米复合材料的OTFT的滞后效应由于界面处捕获的电荷较少而可以显著降低。
