Novel organic inverters with dual-gate pentacene thin-film transistor Jae Bon Koo a, * , Chan Hoe Ku a,b , Jung Wook Lim a , Seong Hyun Kim a a IT Convergence and Components Laboratory, Electronics and Telecommunications Research Institute, Yuseong, Daejeon 305-700, Republic of Korea b Information Display Department, Kyung Hee University, Seoul 130-701, Republic of Korea Received 31 August 2006; received in revised form 28 February 2007; accepted 3 April 2007 Available online 14 April 2007 Abstract We report on the fabrication and characterization of dual-gate pentacene organic thin-film transistors (OTFTs) with plasma-enhanced atomic-layer-deposited (PEALD) 150 nm thick Al 2 O 3 as a bottom-gate dielectric and PEALD 200 nm thick Al 2 O 3 as a top-gate dielectric. The V th of dual-gate OTFT has changed systematically with the application of voltage bias to top-gate electrode. When voltage bias from 10 V to 10 V is applied to top gate, V th changes from 1.95 V to 9.8 V. Two novel types of the zero drive load logic inverter with dual-gate structure have been proposed and fabricated using PEALD Al 2 O 3 gate dielectrics. Because the variation of V th due to chemical degradation and the spatial variation of V th are inherent in OTFTs, the compensation technology by dual-gate structure can be essential to OTFT applications. Ó 2007 Elsevier B.V. All rights reserved. PACS: 72.80.Le Keywords: Organic thin-film transistor; Organic inverter; Pentacene; Threshold voltage; Dual-gate; PEALD 1. Introduction Organic thin-film transistors (OTFTs) are being extensively studied for their potential use in flexible low-cost electronic circuits and switching devices for active-matrix displays [1,2]. The pentacene-based OTFTs have received considerable attention in recent years due to their superior electrical proper- ties such as high field-effect mobility and large on/ off current ratio [1,2]. To date, it was of great inter- est to increase field-effect mobility and downsize the channel length of the transistor for the organic cir- cuits of high switching speed [3]. Inverter is a basic building block used in organic integrated circuits. Complementary technology leads to lower power dissipation, higher noise mar- gin, better stability and easier design of the circuit. Although organic complementary inverters were recently demonstrated using a solution-processed ambipolar OTFT [4] and the integration of both p- and n-type OTFTs on the same substrate [5], most of the OTFT-based circuits reported to date used p-type transistor only because of unstable and easily degraded n-type OTFT. There are two 1566-1199/$ - see front matter Ó 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.orgel.2007.04.001 * Corresponding author. Tel.: +82 42 860 5470; fax: +82 42 860 5202. E-mail address: kjb0706@etri.re.kr (J.B. Koo). Organic Electronics 8 (2007) 552–558 www.elsevier.com/locate/orgel