Investigation of the electrical properties of double-gate dual-active-layer (DG-DAL) thin-film transistor (TFT) with HfO$_{2}$/La$_{2}$O$_{3}$/HfO$_{2}$ (HLH) sandwich gate dielectrics

In this paper, the electrical properties of a double-gate dual-active-layer (DG-DAL) thin-film transistor (TFT) is 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 ($\alpha$-IGZO) is considered as active layer for SAL channel region, and on the other hand, $\alpha$-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, $I_{\operatorname{ON}}/I_{\operatorname{OFF}}$ 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 $\cdot$ 10$^{-3}$ A/$\mu$m, very low OFF-current of 2.53 $\cdot$ 10$^{-17}$ A/$\mu$m, very high $I_{\operatorname{ON}}/I_{\operatorname{OFF}}$ ratio of 1.51 $\cdot$ 10$^{14}$, the threshold voltage of 0.642 V, high mobility of 35 cm$^{2}\cdot$ $v^{-1}$ $\cdot$ s$^{-1}$ and average subthreshold swing of 127.84 mV/dec. A commercial TCAD simulation tool ATLAS from Silvaco$^{\operatorname{TM}}$ is used to investigate all the parameters for considered structures.