Measurement and Modeling of Ambient-Air-Induced Degradation in Organic Thin-Film Transistor

Abstract

The lifetime of organic thin-film transistors (OTFTs) is known to be significantly shorter than that of silicon MOSFETs. It is therefore important to be able to predict their degradation early in the design phase. In this paper, OTFT current characteristic variation is studied in measurements of fabricated devices. In addition, we propose a drain-current simulation model that incorporates temporal parameter variation. The proposed model expresses parameter degradations as changes in threshold voltage and carrier mobility. With the extracted parameters, our proposed model successfully reproduces the temporal performance degradation observed in fabricated devices. We compared our proposed model with existing parameter variation models by fitting with measurement results. Root mean square errors (RMSEs) were calculated for each model. Our proposed model achieved an RMSE of 2.26% whereas that of the existing model was 9.80%. Oscillation frequency degradation in an organic ring oscillator (RO) circuit was also simulated to compare with the measurement results. The simulation results adequately captured the degradation trend observed in the measured results.