二氧化硅栅绝缘层的制备与表面修饰

Preparation and Surface modification of SiO_2 Gate Insulator for Organic Thin Film Transistors

研究了有机薄膜晶体管的二氧化硅栅绝缘层的性质。二氧化硅绝缘层的制备采用热生长法,氧化气氛是O2(g)+H2O(g),工艺为干氧-湿氧-干氧的氧化过程。制得的绝缘层漏电流在10-9 A左右。以该二氧化硅作为有机薄膜晶体管的栅绝缘层,并五苯作为有源层制作了有机薄膜晶体管器件。实验表明采用十八烷基三氯硅烷(OTS)进行表面修饰的器件具有OTS/SiO2双绝缘层结构,可以有效地降低SiO2栅绝缘层的表面能并改善表面的平整度。修饰后器件的场效应迁移率提高了1.5倍、漏电流从10-9 A降到10-10 A、阈值电压降低了5 V、开关电流比从104增加到105。结果显示具有OTS/SiO2双绝缘层的器件结构能有效改进有机薄膜晶体管的性能。

An organic thin-film transistor （OTFTs） with SiO2 gate insulator configuration between gate insulator and source/drain electrodes was investigated. SiO2 insulator layer was prepared by thermal growth method with dryoxygen, wet oxygen, dry-oxygen procedures and O2（g）＋H2O （g）as oxidant. The SiO2 insulator reduced the leakage current to 10^-9A. The OTFTs devices was prepared with the SiO2 insulator and the pentacene was used as an active layer of devices. The results show that the surface energy of the SiO2 gate dielectric is reduced and device flat level is significantly improved by using octadecyhrichlorosilane （OTS）. This OTS/SiO2 bilayer gate insulator configuration increases the field-effect mobility by 1.5 times, reduces the leakage current from 10^-9 to 10^-10A and the threshold voltage by 5 V, and improves the on/off ratio from 10^4 to l0^5 indicating that using OTS/SiO2double-layer of insulator is an effective way to improve OTFT performance.