Current and Gate Capacitance Models of Amorphous InGaZnO Transistors With Double-Layer Electrolytic Gate Insulation

Electrolytic double-layer gate insulation transistors (EDLGITs) have gained significant attention recently due to their features for achieving high-density charge accumulation and low operating voltage. This is primarily attributed to the large capacitance of the electrolyte insulation in these devices. This article proposes a physical model for the capacitance of the electrolytic double-layer gate insulation (EDLGI) and the drain current of amorphous InGaZnO (a-IGZO) EDLGITs based on the channel surface potential. It is demonstrated that the EDLGI capacitance, which comprises the compact-layer and diffuse-layer capacitances, is not only influenced by the characteristics of the electrolyte but also by the gate voltage. Furthermore, the frequency-dependent equivalent capacitance of the electrolyte insulation (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${C} _{\text {eq}}$ </tex-math></inline-formula>) under ac gate voltage in a-IGZO EDLGITs is analyzed. The drain current and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${C} _{\text {eq}}$ </tex-math></inline-formula> calculated using our model show good consistency with the reported experimental data.