Top-gate hybrid complementary inverters using pentacene and amorphous InGaZnO thin-film transistors with high operational stability

Abstract

We report on the operational stability of low-voltage hybrid organic-inorganic complementary inverters with a top-gate bottom source-drain geometry. The inverters are comprised of p-channel pentacene and n-channel amorphous InGaZnO thin-film transistors (TFTs) with bi-layer gate dielectrics formed from an amorphous layer of a fluoropolymer (CYTOP) and a high-k layer of Al2O3. The p- and n- channel TFTs show saturation mobility values of 0.1 ± 0.01 and 5.0 ± 0.5 cm2/Vs, respectively. The individual transistors show high electrical stability with less than 6% drain-to-source current variations after 1 h direct current (DC) bias stress. Complementary inverters yield hysteresis-free voltage transfer characteristics for forward and reverse input biases with static DC gain values larger than 45 V/V at 8 V before and after being subjected to different conditions of electrical stress. Small and reversible variations of the switching threshold voltage of the inverters during these stress tests are compatible with the observed stability of the individual TFTs

Photo-Patternable ZnO Thin Films Based on Cross-Linked Zinc Acrylate for Organic/Inorganic Hybrid Complementary Inverters

“…1−3 Practical circuit designs require the integration of pand n-type TFTs to fabricate complementary logic devices that have low power consumption and provide robust device operation. 4,5 Organic TFTs are particularly useful for p-type components, while metal oxide TFTs are promising n-type counterparts. 6−10 Recently, significant efforts have been devoted to developing high-performance solution-processed metal oxide semiconductors, such as In 2 O 3 , InZnO, and InGaZnO.…”

“…Thin-film transistors (TFTs) based on organic or metal oxide semiconductors have received great interest as low-cost alternatives to traditional silicon-based devices due to their large-area capability and relatively low processing temperatures. − Practical circuit designs require the integration of p - and n -type TFTs to fabricate complementary logic devices that have low power consumption and provide robust device operation. , Organic TFTs are particularly useful for p -type components, while metal oxide TFTs are promising n -type counterparts. − Recently, significant efforts have been devoted to developing high-performance solution-processed metal oxide semiconductors, such as In 2 O 3 , InZnO, and InGaZnO. − However, all these materials contain a considerable amount of indium, which is scarce and expensive, making widespread utilization of indium-containing materials in mass-produced electronic devices unlikely. − It is therefore desirable to develop metal oxide TFTs based on resource-friendly materials, such as ZnO, which is naturally abundant and cost-efficient …”