有源层厚度对CuPc-OTFT器件性能的影响

Active Layer Thickness Dependence of Electrical Properties of Top Contact Organic Thin Film Transistor Based on Copper Phthalocyanine

研究了不同厚度有源层的顶电极CuPc OTFT器件的电学特性。发现器件的性能与有源层厚度有依赖关系,其中,有源层厚度为20nm的器件性能最好。在有源层厚度大于20nm时,有源层厚度的增大不但分去一部分栅电压而且还增大了源、漏电极的接触电阻,从而不利于器件性能的提高。但当有源层厚度小于20nm以后器件的性能开始降低。我们认为当有源层厚度降低到一定程度时,有源层上表面的表面态会使有机材料的隙态浓度增加从而对沟道载流子迁移率产生不良影响以及使器件的阈值电压增大。

The device properties of copper phthalocyanine(CuPc)-based top contact organic thin film transistors(OTFTs) with various active layer thickness were investigated. The operating performance of the OTFTs depended on the thickness, and a device with a CuPc layer of 20 nm showed the optimum property. The poor performance of OTFTs with active layer thickness larger than 20 nm was attributed to thicker active layer sharing more gate voltage and offering more contact resistance. For poorer performance of the devices with active layer thinner than 20 nm, it was deduced that the back surface of a very thin active layer can introduce located states into the gap of organic materials, which can decrease the field-effect mobility of OTFTs and increase threshold voltage of OTFTs.