A High Voltage Gain Inverter Integrated With Enhancement- and Depletion-Mode a-InGaZnO Thin-Film Transistors

In this article, amorphous indium–gallium–zinc oxide (a-IGZO) inverter integrated with enhancement-mode (E-mode) and depletion-mode (D-mode) thin-film transistors (TFTs) with the record high voltage gain of 372 V/V is demonstrated. The D-mode a-IGZO TFTs are realized by local hydrogen plasma treatment, which induces hydrogen doping in the a-IGZO film. The X-ray photoelectron spectroscopy (XPS) measurements prove that the hydrogen doping process increases the oxygen vacancies and free electron concentration in the a-IGZO. Therefore, the doped-hydrogen causes a negative shift in threshold voltage ( ${V} _{\text {th}}$ ) and improves the field effect mobility ( $\mu _{\text {FE}}$ ). After carefully optimizing the process of hydrogen plasma treatment, the inverter with a D-mode load is fabricated. The proposed inverter shows excellent performance, including a wide output swing range of almost 100%, a narrow transition region of 0.05 V, and a remarkable voltage gain of 372 V/V.