A reliable and efficient small‐signal parameter extraction method for GaN HEMTs

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This paper presents the temperature dependence of small signal performance of GaN-on-diamond high electron mobility transistors (HEMTs) at an ambient temperature range from 0°C to 125°C. The temperature influence on the parasitic resistances together with the intrinsic parameters is investigated, and the temperature coefficients of these parameters are extracted from measured data. For comparison, a GaN-on-SiC device is also investigated. These results are important for the development and application of the GaN-on-diamond HEMT technology. KEYWORDSGaN-on-diamond, high electron mobility transistor (HEMT), small signal parameters, temperature dependence

Section: Resultsmentioning

confidence: 61%

Section: Extraction Proceduresmentioning

confidence: 99%

Section: Extraction Proceduresmentioning

confidence: 99%

Section: Extraction Proceduresmentioning

confidence: 99%

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Temperature‐dependent small signal performance of GaN‐on‐diamond HEMTs

Zhou²,

Kong³

et al. 2019

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“…The nonlinear gate capacitances C gs and C gd are modeled with a modified Angelov model. 11 The extrinsic and intrinsic capacitances, inductances, and resistances of the equivalent circuit model are extracted from measured multibias S-parameters up to 50 GHz at different ambient temperatures (T amb ) using the method we proposed in Chen et al and Wen et al 43,44 It has been found that the extrinsic inductances and capacitances are nearly temperature independent in accord with the expectation of a minimal temperature sensitivity. 45 The gate parasitic resistance (R g ) consists mainly of the gate metallization resistance; thus, it exhibits an increase with T amb as shown in FIGURE 9 The calculated low-field mobility of 2DEG versus temperature together with the contribution of each scattering mechanism FIGURE 10 Variation of drain current I ds with V ds at normal temperature for the GaN heterojunction high electron mobility transistors (HEMT) device when self-heating is considered (solid lines).…”

Section: Resultsmentioning

confidence: 76%

Improved quasi‐physical zone division model with analytical electrothermal I_ds model for AlGaN/GaN heterojunction high electron mobility transistors

Yong-bo

Wang³

et al. 2019

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An accurate analytical electrothermal drain current (I ds ) model for AlGaN/GaN HEMTs is presented in this letter. The model is implemented into our recently proposed quasi-physical zone division (QPZD) model for demonstration purpose. Compared with the original QPZD model, its electrothermal characteristics are enhanced by involving more fundamental temperature dependent elements. In addition, these elements are derived analytically based on physical mechanisms instead of former pure empirical fitting method. Thus, the extracted parameter values are more close to intrinsic values. An in house 0.15-μm GaN HEMT is used for validation. Compared with the measured data at a wide ambient temperature range (245-390 K), this electrothermal model demonstrates good accuracy to predict the DC characteristics and RF performances of GaN HEMTs.relatively simple while still provides a reasonable prediction on the device performance under different operating conditions. This large-signal modeling approach is usually based on the current and charge sources obtained by integration. 9,10 C. Wang et al 11 presented a temperature dependent large signal model for GaN HEMTs, which includes thermal, trapping, and RF dispersion effects. However, the method proposed in the present paper was to modify the Chalmers model that was originally proposed by I. Angelov 12,13 and is basically an empirical model. Empirical models for GaN HEMTs 14-18 usually contain dozens of fitting parameters, thus hardly offer an opportunity to understand device operation from the physical point of view.Compared with empirical models, physics-based analytical models for GaN HEMTs have been widely caught the attention in recent years 19-25 because they originate from device operation principle and contain most of the device physical parameters and much less empirical ones. Previously, we proposed an analytical model named quasi-physical zone division (QPZD) model 26,27 for GaN HEMTs. Compared with other fully physics-based analytical models, the QPZD model shows some advantages, such as concise formulas with superior accuracy, fewer parameters, better convergence, etc. However, empirical fitting functions are introduced to the electron sheet density n s and the critical electric field E c , which lack of clear physical meanings. Besides, only a few of the temperature dependent elements, such as the pinch off voltage V off and the maximal electron saturated velocity υ sat are included in the model. These two factors may result in unreasonable parameter values. For example, the obtained variation of the low-field mobility μ 0 with temperature is unreasonably large in our previous QPZD model. 27 The aim of this work is to improve the electrothermal characteristics of the QPZD model to incorporate the temperature effects on device performance. The effects of temperature variation on the fundamental elements (ie, ϕ B , E g , μ 0 , υ sat , and k) and also on the deduced ones (ie V off , n s , the thermal resistance R th , the maximal drain current I max , E c ) are inc...

Guest Editorial for the special issue on devices and circuits for millimeter‐wave and THz applications

2020

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Wireless communication, precision guidance, imaging, internet of things, and biomedical applications in the millimeter-wave and THz bands promise new functionalities that cannot be provided by present systems. Different from present design methods, new design methods are required to support the development of high-performance millimeterwave and THz band devices and systems. These new design methods should incorporate new materials, advanced processing and technologies, and can accurately account for multi-physics coupling effects. This special issue collects 32 papers including 20 papers on active device modeling, nine papers on passive device and circuit modeling and design techniques, and three papers on emerging system applications.Active devices for state-of-the-art millimeter-wave and THz systems discussed in this special issue include Indium phosphide (InP) heterojunction bipolar transistors (HBTs), Indium Gallium Phosphide (InGaP)/Gallium arsenide (GaAs) HBTs, Gallium nitride (GaN) high electron mobility transistors (HEMTs), GaAs HEMTs, complementary metal oxide silicon (CMOS) transistors, and electric vacuum devices. The discussion covers the important device features of high frequency, high power, low noise, and high efficiency. As the frequency goes up to the millimeter-wave and THz bands, advanced physical-based or SPICE-like equivalent circuit and compact models are needed. As a solid-state device, InP transistor can operate at a very high frequency by taking advantages of extremely high electron mobility. Zhang et al 1 presented a review on the compact modeling of InP HBTs for THz integrated circuits. Useful improvements made for HBTs are reported on the analysis of intrinsic base resistances by Chen et al, 2 on large-signal models by Hu et al, 3 on the determination of cutoff and maximum oscillation frequencies by Zhang and Gao, 4 and on the thermal resistance calculation by Wang et al. 5 Due to a high breakthrough voltage and saturation velocity, GaN HEMTs is very promising for millimeter-wave solid-state power amplifiers. Chen et al 6 reported an improved quasi-physics zone division large-signal model to account for electro-thermal effects, which is valid for the ambient temperature range of 245 to 390 K. Physical parameters' effects, reliable parameter extraction, and dynamic thermal impedance extraction for the equivalent circuit models of GaN HEMTs are discussed by Mi et al, 7 Chen et al, 8 and Wang et al, 9 respectively. The modeling of emerging devices is also presented by Chen et al 10 for GaN-on-diamond HEMTs and Zhang et al 11 for AlGaN/GaN fin-shaped HEMTs, which may be interesting for next generation devices. Accurate modeling of transistors' noise performance is important for low-noise applications. Jarndal et al 12 developed a noise model for GaN HEMTs and Caddemi et al 13 reported an improved scalable parameter extraction method for GaAs HEMTs. CMOS transistor is very competitive in millimeter-wave and THz circuits due to its mature process. Bashir et al 14 presented a scalable small-...