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

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, SiO 2 ) is replaced with a tri-high- k gate dielectric layer, hafnium dioxide (HfO 2 )/lanthanum oxide (La 2 O 3 )/hafnium dioxide (HfO 2 )—(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, I ON / I OFF 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 I ON / I OFF ratio of 1.51 × 10 14 , threshold voltage of 0.642 V, high mobility of 35 cm 2 v –1 s –1 and average subthreshold swing of 127.84 mV/dec. A commercial TCAD simulation tool ATLAS from Silvaco TM is used to investigate all the parameters for considered structures.