Conduction and low-frequency noise are analyzed in hydrogenated amorphous thin film transistors with small channel length. From current–voltage characteristics a set of conduction parameters is extracted pointing out parasitic resistances in series with the active channel. The low-frequency noise behavior is studied by means of the small equivalent circuit of the device. Intrinsic channel noise is separated from access resistance noise. Channel noise variations versus device biases agree with Hooge’s theory (carrier mobility fluctuations) but the noise levels are greater than in crystalline metal-oxide-semiconductor transistors. For high drain current 1/f noise in access series resistances prevails and becomes the main noise source. So, the results show the important part taken by these resistances in conduction and noise. Some comments for the design of thin film transistors are given.
1/f noise investigations in thin film transistors with long channel and thin thickness of amorphous silicon film are presented. It is found that the noise behavior follows the mobility fluctuation model in ohmic and saturation regimes, whereas in the subthreshold conduction, a quadratic law versus the drain current is observed. The noise modeling is proposed taking into account the equations usually utilized for crystalline silicon metal–oxide–semiconductor field-effect transistors according to Hooge’s theory. Moreover, the Berkeley Short-Channel Insulated Gate Field-Effect Transistor Model is adapted to predict the noise levels. Two noise parameters have been extracted: The first is used in the subthreshold region, whereas we show that the second, directly related to Hooge’s parameter, is adequate to describe alone the noise in normal conduction up to the saturation.
An approach to model 1/f noise in the weak inversion range of metal–oxide–semiconductor transistors (MOST) is proposed, based on Hooge’s theory (mobility fluctuation model). Starting from conduction equations in the subthreshold regime, a method to evaluate the total number of carriers under the gate is presented and allows us to deduce the Hooge parameter αH. This model is applied to p-channel MOSTs. With the proposed model, the value of αH obtained in weak inversion is quite similar to this extracted in strong inversion allowing a unique description of the 1/f noise.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.