The Effect of Sampling Interval and Various Difference Approximation Methods on Extracting the Subthreshold Swing in InGaZnO Thin Film Transistor

In this work, the effect of gate voltage sampling interval (
$\Delta \text{V}_{\mathrm {gs}}$
) and various difference approximation methods on extracting the value of subthreshold swing (SS) have been investigated in detail for InGaZnO thin film transistor (TFT). The values of extracted SS under the
$\Delta \text{V}_{\mathrm {gs}}$
altered from 1 V to 0.03125 V for the same InGaZnO TFT exhibit a large disparity and the minimum value of SS with
$\Delta \text{V}_{\mathrm {gs}}$
of 0.03125 V has 3~4 times less than the
$\Delta \text{V}_{\mathrm {gs}}$
of 1 V by the same approximation method. Furthermore, the impact of various difference approximation methods on extracting SS have also been involved. Moreover, an empirical formula is proposed to estimate the proper sampling interval for accurate approximating the SS. The proposed phenomenon and method in this work could be a meaningful reference for extracting the SS and other parameters in InGaZnO TFTs.