Efficiency of AlGaN/GaN HEMTs used in high power, high frequency applications is thought to be limited by parasitic thermal effects. In this study, we investigate coupled electrical and thermal transport in AlGaN/GaN HEMTs using an ensemble Monte Carlo model. Calculation of the non-equilibrium phonon population reveals a hot spot in the channel that is localized at low drain-source bias, but expands towards the drain at higher bias, significantly degrading channel mobility.

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A multiphysics model was developed to describe the evolution of the electrical and thermal behavior along with the mechanical stress fields in AlGaN/GAN heterostructure field-effect transistors and metal-oxide semiconductor heterostructure field-effect transistors under operational conditions. The electric field and power dissipation were obtained from Maxwell's equations. A one-way coupling procedure between the electrical and thermo-mechanical model was utilized to estimate the peak temperature and thermal stresses in these devices. By coupling the solutions, the direct impact of the electrical performance on the thermal stresses in these devices was analyzed.

The two-dimensional quantum well laser simulator Visible Laser Simulator (VLS) has been extended to simulate III-V nitride based lasers. In this paper, we present details about the laser simulator and focus on the six band k.p solver used to calculate the electronic band structure. The effect of strain on bulk and quantum well electronic dispersion is analyzed, and the influence of the built-in polarization charges on the band diagram is likewise considered.

The influences of temperature, dopant density, freecarrier density, and field orientation on the electron drift mobility and velocity-field relationship in wurtzite c-axis GaN are quantified by means of theoretical investigation. Electron velocity perpendicular to the growth plane is uniformly lower than that parallel to the growth plane for field strengths below 500 kV/cm, although anisotropy within the basal plane itself is found to be insignificant. The calculated low-field electron mobility is demonstrated to be consistent with recent Hall measurements over a range of dopant densities. Low-field mobility is enhanced under the influence of free-carrier densities above the background doping due to both increased screening of ionized impurities and a reduction in A1-LO phonon lifetime through the plasmon-phonon interaction.Index Terms-Electron velocity, ionized impurity, phonon population, wurtzite gallium nitride (GaN).