A Film-Profile-Engineered 3-D InGaZnO Inverter Technology With Systematically Tunable Threshold Voltage

In this paper, a new depletion-load metal oxide-based inverter with 3-D structure is realized with film-profile-engineered InGaZnO (IGZO) thin-film transistors (TFTs). The proposed inverter possesses vertically stacked load and drive TFTs whose threshold voltage can be flexibly adjusted into a wide range of -2.3-1 V through merely adjusting the geometric parameters without the necessity of additional processes or masks. The 3-D IGZO inverters constructed through the proposed technology demonstrate full-swing switching with voltage gains up to 19 V/V under an operation voltage of 9 V. The 3-D inverters can not only reduce the footprint but also promote the resistance toward light-induced instability.