Analysis of Carrier Behavior for Amorphous Indium Gallium Zinc Oxide After Supercritical Carbon Dioxide Treatment

Abstract Amorphous indium gallium zinc oxide (a‐IGZO) thin‐film quality can be enhanced using supercritical carbon dioxide (SCCO₂). How to verify specific and accurate mechanism for the carriers inside an a‐IGZO layer before and after the SCCO₂ treatment is worth investigating. This work designs a‐IGZO thin film transistors with different channel thicknesses (41, 28, and 19 nm), treats them using SCCO₂, and analyzes the change in carrier behavior. The effect of the SCCO₂ on both carrier density and carrier transport is investigated using energy band information, Technology Computer Aided Design (TCAD) simulations on density of states and resistance analyses. After the treatment, the thinner channel thickness exhibits better drivability enhancement. That is because of the fewer traps and smoother carrier transportation path resulted from better M−O−M frameworks, and decreased M−OH bonds as well as interface charges. Besides the traditional analysis methods and TCAD simulations, layer‐by‐layer X‐ray photoelectron spectroscopy and sheet resistance measurement are also applied to verify the detailed carrier mechanism behind different phenomena.