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

Abstract

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...

Optimization based on electro-thermo-mechanical modeling of the high electron mobility transistor (HEMT)

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A scalable electrothermal model using a three‐dimensional thermal analysis model forGaN‐on‐diamondhigh‐electron‐mobility transistors

“…Temperature strongly affects the reliability and performance of devices, as highlighted in articles that analyze how the ambient and self‐heating effects lead to changes in the device performance and small‐ and large‐signal outputs. Other studies have focused on how other device characteristics depend on temperature 19,20 . Because the temperature of power transistors is determined primarily by the thermal conductivity of the internal material, the use of diamond materials with high thermal conductivity can significantly reduce the thermal resistance of devices.…”

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“…Gallium nitride GaN is characterized by high mobility, very high electrical breakdown field and high thermal conductivity [5,6]. Thanks to these characteristics, these components have been used in different high-temperature and high-frequency applications [7,8], such as airborne systems, telecommunication and electronic warfare [9,10]. HEMT has also been used in several systems such as high-power amplifiers, satellites and radars [11].…”