Quantum Confinement and Interface States in ZnO Nanocrystalline Thin-Film Transistors

摘要: The experimental current–voltage ( ${I}_{D}$ – ${V}_{G}$ ) and capacitance–voltage ${C}$ characteristics of the bottom-gate/top-contact ZnO thin-film transistors (TFTs) are analyzed accounting for quantum confinement interface state effects. All measurements performed on same TFTs composed a 45-nm-thick nanocrystalline channel, indium tin oxide gate electrode, 21-nm-thick Al2O3 insulator. Interface density (Dit) derived from combined high–low frequency capacitance method reveals large Dit near conduction band edge. TFT simulated using Schrodinger–Poisson model compared to semiclassical model. calculates lower C in accumulation by correctly peak carrier concentration being several nanometers away ZnO/Al2O3 interface. fit error strong is only 1.2% 4% simulations. simulations 21 nm Al2O3. An effective mobility $\mu _{\mathrm{ eff}}$ that increases linearly with voltage ratio mobile charge per unit area channel. Ignoring overestimates channel hence underestimates 40%. additional profile, at top ZnO, proposed our analysis explain subthreshold region.