We propose a unified DC and flicker noise model for bottom-gate amorphous InGaZO (a-IGZO) thin film transistors (TFTs) with an etch stop layer (ESL) valid for subthreshold, linear, and saturation regimes. A recent study carried out by our group about the origin of 1/f noise in four ESL a-IGZO TFTs with gate lengths 15, 20, 30, and 50μm and a width of 100μm revealed that carrier number fluctuation is the dominant mechanism of flicker noise in these specific devices and the contact resistances do not significantly contribute to the overall noise level. In this paper, we extended the work to develop a physics based 1/f noise model for ESL a-IGZo TFTs. The unified model and parameter extraction method, a technique developed for accurate parameter extraction and modeling of TFT device characteristics, is adapted to develop the I-V model. The noise model is subsequently derived taking into account the observed correlated mobility fluctuation based on the unified 1/f noise modeling idea. Results showed an excellent agreement between the experimental and modeled data for both the DC and flicker noise behavior of sample ESL a-IGZO TFTs over a broad range of bias conditions, at 298, 315, and 333 K operating temperatures.
Physics based threshold voltage (V th ) models for Al x GaN 1-x /AlN/GaN and double channel (DH-Al x GaN 1-X ) HEMT devices are presented. Based on the concept that donor like surface states located on the AlGaN top are the source of electrons in the 2DEG, analytical Schottky barrier height (ϕ b ) expression is derived and used in the development of the threshold voltage models. The calculated V th values for sample AlGaN/AlN/GaN and DH-Al x GaN 1-X HEMT devices are consistent with the values extracted from published experimental data. Moreover, the V th models are incorporated in a recently proposed charge based I-V model for GaN HEMTs and DC characteristics of the devices under test are simulated. The model predictions are strongly correlated with experimental data in both the output and transfer characteristics cases over a full range of biasing conditions.
In this paper, Low Frequency Noise (LFN) characterization of SP500 polymer-based Organic Thin Film Transistors with a nonfluorinated dielectric material is presented. The work aimed at identifying the mechanism of 1/f noise as well as inspecting the quality of the gate dielectric interface. Analysis of the LFN experimental data reveals that the 1/f noise power spectral density (PSD) follows 1/f γ frequency dependence over 1 Hz–10 kHz range. The normalized current noise PSD is found to vary similar to the squared-transconductance drain current ratio with respect to drain current, and is inversely related to the gate-area. Furthermore, the high carrier mobility (on the order of 2–3 cm2/Vs) obtained in these devices indicates that low density of traps exists in the semiconducting organic thin film. Such results ascribed the origin of 1/f noise to the dynamic exchange of charge carriers between the gate-dielectric traps and the channel. In addition, Nst values extracted from the 1/f noise experimental data reflect the enhanced quality of the gate dielectric and the interface it forms with the channel material.
In this paper, the flicker noise properties of bottom-gate ESL structured amorphous InGaZnO (a-IGZO) thin-film transistors (TFTs) from two different technologies have been studied and modeled. Model development is carried out by adapting the Unified Model parameter Extraction Method (UMEM), developed for parameter extraction and compact modeling of TFT devices, and the unified 1/f noise model. Furthermore, comparative study of device figures of merits is performed to point out the device performance enhancements that the different fabrication technologies have brought about. It is found out that both devices have low deep state density, whereas the second device demonstrated higher performance in terms of carrier mobility and subthreshold slope. Both the DC and noise models are validated by matching them against experimental data obtained in different regimes of device operation.
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