Transient behavior of the a-Si : H/Si<sub>3</sub>N<sub>4</sub> metal–insulator–semiconductor (MIS) capacitor and its relationship to the performance of a-Si:H based active-matrix liquid crystal displays (AMLCDs) have been analyzed in detail. A relatively slow voltage decay whose time constant is comparable to the frame period of the LCD is observed after applying a voltage pulse that drives the MIS capacitor into the electron accumulation. The voltage decay is due to electron emission from the localized states at the a-Si : H/Si<sub>3</sub>N<sub>4</sub> interface. It is also found that this voltage transient results in a shift in the optimum common voltage for the liquid crystal pixel by changing the temperature and light exposure when an MIS-type capacitor is inserted between the pixel electrode and the adjacent gate bus-line as the storage capacitor. This shift in the optimum common voltage affects the image quality of AMLCDs through image sticking or flicker. A similar effect can occur even without an MIS-type storage capacitor in high resolution AMLCDs, where the gate-source parasitic capacitance of the thin—film transistor is comparable to the net capacitance of the pixel. It is important to take such transient effects of MIS capacitors into consideration in pixel designing.
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