Ta2 O5-PMMA复合栅绝缘层对OFETs性能的影响

摘要

选用五氧化二钽(Ta2 O5)-聚甲基丙烯酸甲酯(PMMA)复合材料作为栅绝缘层制备了并五苯有机场效应晶体管(OFETs)。通过在 Ta2 O5表面旋涂一层 PMMA 可以降低栅绝缘层的表面粗糙度，增大其场效应晶体管的迁移率。研究了厚度在20~60 nm 范围内的 PMMA 对复合绝缘层表面形貌、粗糙度以及器件电学性能的影响。结果表明，当 PMMA 厚度为40 nm 时，器件的电学性能最佳。与单一的 Ta2 O5栅绝缘层器件相比，其场效迁移率由4.2×10-2 cm2／(V·s)提高到0.31 cm2／(V·s)；栅电压增加到-20 V 时，开关电流比由2.9×102增大到2.9×105。%This paper reports pentacene field effect transistors (OFETs) with a gate insulator made of compound Ta2 O5-PMMA where PMMA (poly (methyl methacrylate)) is spin-coated onto the top of evaporated layer of Ta2 O5 . A comparison with devices with only Ta2 O5 is presented. The latter not only shows a high surface roughness but also exhibits very low field-effect mobility. These drawbacks can be overcome by depositing a PMMA layer on Ta2 O5 . The influence of PMMA thickness in the range 20 - 60 nm is presented. The results show that when the thickness of PM-MA is approximately 40 nm, the electrical performance of OFETs is optimal. Compared with conventional OFETs, the field-effect mobility increases from 4. 2 × 10 - 2 to 0. 31 cm2 / (V·s), and the on/ off current ratio increases from 2. 9 × 102 to 2. 9 × 105 when the gate voltage increases to - 20 V.