This article presents extraction of small signal model parameters and TCAD simulation of novel asymmetric field plated dual material gate AlGaN/GaN HFET first time. Small signal model is essential for design of LNA and microwave electronic circuit by using the proposed superior performance HFET structure. Superior performances of device are due to its dual material gate structure and field plate that can provide better electric field uniformity, suppression of short channel effects and improvement in carrier transport efficiency. In this article we used direct parameter extraction methodology in which S-parameters of device were measured using pinchoff cold FET biasing. The measured S-parameters are then transformed into Y-parameters to extract capacitive elements and then in to Z-parameters to extract series parasitic elements. Intrinsic parameters are extracted from Y-parameters after de-embedding all parasitic elements of devce. Microwave figure of merits and dc performance are also studied for proposed HFET. The important figure of merits of device reported in the paper include transconductance, drain conductance, current gain, transducer power gain, available power gain, maximum stable gain, maximum frequency of oscillation, cut-off frequency, stability factor and time delay. Reported results are valdated with experimental and simulation results for consistency accuracy. Keyword:Cutoff frequency HEMT model Microwave figure of merits Parameters extraction Small signal model
In this paper we present 2-D analytical model for I-V characteristics and transconductance of dual channel AlGaN/GaN Modulation Doped Field Effect Transistor (DC-MODFET) to demonstrate the current-voltage as well as transfer characteristics of the device structure under different bias conditions. The model analyses sheet charge density and finaly current density in each of the top and bottom channels using effective device threshold expressions based on spontaneous and piezoelectric polarization dependent two dimensional electron gas (2-DEG). An aluminum mole fraction graded doping profile in bottom barrier layer has been used for bottom channel sheet carrier density. Trapping/detrapping surface states are also considered to determine device drive current and trans-conductance expressions. The presence of double channels in the device minimize the current collapse problems, is accurately explained in our proposed model. The current collapse that occurs more in the top channel nearer to the gate, is subsidized by the current in bottom channel, hence minimizing overall current collapse in the device. Finally, the numerical predictions from our model are compared with the published experimental results and found to be in close agreement.
Purpose This paper aims to report small-signal parameter extraction and simulation of enhanced dual-channel dual-material gate AlGaN/GaN high electron mobility transistor (HEMT) for the first time for the characterization of a device in microwave range of frequency. Design/methodology/approach For parameter extraction, a standard and well-known direct parameter extraction methodology is applied. Extrinsic elements of small-signal circuit model are extracted from measured S-parameters obtained using pinch-off cold field effect transistor (FET) biasing in the first step at a low frequency range and at a higher frequency range in the second step to ensure higher extraction accuracy. Intrinsic elements are extracted from intrinsic Y-parameters that are obtained after de-embedding all the extrinsic parasitic elements of the device. Figure of merits of radio frequency are also derived from the measured results and S-parameters of the proposed device. Findings Small signal parameters of the proposed device circuit model are extracted using the standard direct parameter extraction technique. Analysis of microwave figure of merits for device include maximum oscillation frequency, cut-off frequency, current gain, transducer power gain, available power gain, maximum stable gain, transconductance, drain conductance, stern stability factor and time delay. Practical implications The paper bridges the gaps between theory and experimental practices by validating extracted results with reported results of structurally matching devices. Originality/value An enhanced device structure investigated for small signal parameters incorporates field plate over dual metal engineered gate to provide better electric field uniformity, effective suppression of short channel effect, reduction in current collapse, improvement in carrier transport efficiency and enhancement in drain current capabilities.
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