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The IUP Journal of Electrical and Electronics Engineering:
A Compact Analytical Model of AlGaN/GaN MODFET for Microwave Applications
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The paper develops an analytical model of AlGaN/GaN Modulation Doped Field Effect Transistor (MODFET). The 2-DEG is calculated as a function of device dimensions and doping density. The current-voltage characteristics developed from the 2-DEG model includes the effect of field dependent mobility, velocity saturation and parasitic source/drain resistances. A high saturation current of 501 mA/mm at a gate bias of 1 V has been obtained for a gate length of 50 nm. The results so obtained are in close agreement with previously published results which confirms the validity of the proposed model.

 
 

AlGaN/GaN-based High Electron Mobility Transistor (HEMTs) have recently attracted considerable attention due to their potentialities for high voltage and high power operations in microwave applications (Campbell et al., 2009). Due to their excellent material properties, AlGaN/GaN HEMTs have abilities such as high efficiency and high gain associated to high voltage operation and wide band gap leading to high breakdown voltage and high saturated electron drift velocity (Zhang et al., 2014). Due to a broad spectrum of applications, the demand for large quantities of HEMT device is increasing (Ahlawat et al., 2007). Recently, tremendous progress has been recorded in the material quality and device processing of GaN-based HEMTs (Hou et al., 2012). The superior properties of GaN are adequate for power applications despite its high effective electron mass and small low field mobility compared to AlGaAs (Wu et al., 2001). These have resulted in significant improvements in the DC and RF performance of these devices (Jos, 2013) GaN-based HEMTs can achieve a two-dimensional electron gas sheet carrier density well above 1013cm–2 very easily as compared to other III-V compound semiconductor-based devices (Ambacher et al., 2000). The large conduction band discontinuity between AlGaN and GaN alone cannot allow such values of ns (Wei et al., 2014). Thus, the presence of a large polarization field at the heterointerface, producing a strong conduction band bending and an increased carrier confinement has been suggested to account for the high value of sheet carrier density (Kumar et al., 2013).

 
 
 

Electrical and Electronics Engineering Journal, Modulation Doped Field Effect Transistor (MODFET), 2-DEG sheet charge density, Transconductance, Drain conductance