Modified Conductance Method for Extraction of Subgap Density of States in a-IGZO Thin-Film Transistors

Geometry-Based Tunability Enhancement of Flexible Thin-Film Varactors

“…A lower number of fingers also lowers the capacitance in depletion contributing to the presented tunability dependence, while the accumulation capacitance stays constant. Additionally, a frequency dispersion of the C-V characteristics and therefore of the tunability is visible, which is in agreement with observations of the gate capacitance of a-IGZO TFTs [20]. This can be attributed to the a-IGZO resistance in accumulation and the fact, that for increasing frequency, the charging and discharging of the trap states can not follow the applied voltage and their contribution to the semiconductor capacitance decreases [21].…”

Analysis of frequency dispersion in amorphous In–Ga–Zn–O thin-film transistors

“…All these techniques make certain initial assumptions about the free carrier density, mobility, and other material parameters. To circumvent these issues, frequencydependent capacitance-voltage (CV) measurements are used to retrieve information about the subgap states as no assumptions regarding the material properties are required in this case [9,10]. The CV technique for trap extraction is based on the assumption that there are two contributions to the semiconductor capacitance.…”

Unified Subthreshold Coupling Factor Technique for Surface Potential and Subgap Density-of-States in Amorphous Thin Film Transistors

“…For process optimization and practical application of a-IGZO TFTs to their circuits and systems, extraction of the subgap densityof-states [DOS; g(E)] over the bandgap is important because it determines the long-term instability as well as the electrical properties. There are useful reports on the extraction of g(E) in a-IGZO TFTs using the capacitance-voltage (C-V ) characteristics [3], [4], photo-induced shift of the threshold voltage (V T ) [5], and numerical simulation [6]. However, the optical and electrical effects may cause a drift of intrinsic characteristics during the extraction process.…”

“…However, the optical and electrical effects may cause a drift of intrinsic characteristics during the extraction process. Furthermore, in the nonlinear relation between the gate voltage (V GS ) and the surface potential (ψ S ) of the active layer, the frequencydispersive C-V characteristics with parasitic capacitances and resistances [4], [7], and a complicated calculation procedure Manuscript with stress-induced measurement [8] gives incorrect nonlinear mapping of the gate voltage to the energy level. We also note that any technique employing C-V data for characterization of surface potential and/or subgap DOS should face a limited availability for scaled TFTs with extremely small device area [9].…”