Investigation of the Electrical Properties of Double-Gate Dual-Active-Layer (DG-DAL) Thin-Film Transistor (TFT) with HfO
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HYSICS OF SEMICONDUCTOR DEVICES
Investigation of the Electrical Properties of Double-Gate Dual-Active-Layer (DG-DAL) Thin-Film Transistor (TFT) with HfO2|La2O3|HfO2 (HLH) Sandwich Gate Dielectrics L. Ramesha, S. Moparthia, P. K. Tiwarib, V. R. Samojuc, and G. K. Saramekalaa,* a Department
of Electronics and Communication Engineering, NIT Calicut, Kozhikode, 673601 India b Department of Electrical Engineering, IIT Patna, Patna, 801103 India c Department of Electronics and Communication Engineering, Gayatri Vidya Parishad College of Engineering, Vishakapatnam, 530048 India *e-mail: [email protected] Received March 11, 2020; revised March 11, 2020; accepted June 9, 2020
Abstract—In this paper, the electrical properties of a double-gate dual-active-layer (DG-DAL) thin-film transistor (TFT) are investigated. To increase the ON-current and pixel intensity, and control the voltage stress bias, the conventional gate oxide material (silicon dioxide, SiO2) is replaced with a tri-high-k gate dielectric layer, hafnium dioxide (HfO2)/lanthanum oxide (La2O3)/hafnium dioxide (HfO2)—(HLH). Further, the performance of the proposed DG-DAL structure is compared with the single-active-layer (SAL) and dual-active-layer (DAL) TFTs. The amorphous indium-gallium zinc-oxide (a-IGZO) is considered as active layer for SAL channel region, and on the other hand, a-IGZO and indium-tin-oxide (ITO) are considered as active layers for DAL TFT and DG-DAL TFT channel regions. The parameters such as OFF-current, ON-current, ION/IOFF ratio, threshold voltage, mobility, average subthreshold swing, etc. are evaluated for the considered structures. It is observed that the DG-DAL TFT with HLH dielectric offers high ON-current of 3.85 × 10–3 A/μm, very low OFF-current of 2.53 × 10–17 A/μm, very high ION/IOFF ratio of 1.51 × 1014, threshold voltage of 0.642 V, high mobility of 35 cm2 v–1 s–1 and average subthreshold swing of 127.84 mV/dec. A commercial TCAD simulation tool ATLAS from SilvacoTM is used to investigate all the parameters for considered structures. Keywords: single active layer (SAL), dual active layer (DAL), double-gate dual active layer (DG-DAL), InGaZnO (IGZO), InSnO (ITO), thin-film transistor (TFT), HfO2/La2O3/HfO2 (HLH) DOI: 10.1134/S1063782620100243
1. INTRODUCTION Amorphous oxide semiconductor (AOSs) progresses as a dominant player in the state of the art large panels and high-resolution display devices owing to high carrier mobility, low-temperature processing, better visible transparency, large-area uniformity, and high flexibility [1, 2]. Amorphous oxide semiconductors can be used in active-matrix liquid-crystal display (AMLCD) devices, active-matrix organic light-emitting diode (AMOLED) displays, and in the back panel of liquid crystal displays (LCDs) [3, 4]. However, the mobility offered by a single-active-layer (SAL) amorphous hydrogenated silicon (a-Si:H) thin-film transistor (TFT) is 30 cm2 v–1 s–1) due to their high pixel densities. Replacing SAL with the DAL is one of the possible solutions to meet such high mobility [1
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