With decreasing transistor size,the self-heating effect of devices has received more and more attention.To accurately describe the local hot spots generated in transistor devices by electron-phonon coupling,this paper presents a coupled electron-phonon Monte Carlo method with an iterative solution by taking gallium nitride high-electron-mobility transistor as the research object.The electron Monte Carlo method is used to simulate the electron transportation process,and the phonon Monte Carlo method is used to simulate the phonon transport process.Both these methods are solved iteratively by transferring the heat source and temperature field information.The temperature effect of hot spots is studied by applying different temperature fields in the electron Monte Carlo method.After temperature rises,emission phonons at the peak hot spot decrease,the contribution of high-frequency phonons increases,and power density at the peak hot spot increases linearly.Furthermore,power density increases by 1 × 1016 W/m3 for every 1-K temperature rise.Once the iterative solution converges,heat generation power density and peak temperature increase,and the increased amplitude is affected by the initial value.When phonon transport under a hot spot is decomposed,the heat flux contribution of low-frequency phonons increases due to their larger specific heat capacity and group velocity.Under the influence of hot spots,the contribution of high-frequency phonon on heat flux increases by up to 35％.The selective excitation of hot spots causes nonequilibrium among phonon modes,which hinders the heat transport process to a certain extent.This work shows the importance of temperature iteration in the electron-phonon coupling process and provides a reference for the self-heating effect simulation of transistors.
关键词
GaN/HEMT/电子-声子耦合/蒙特卡罗方法/温度效应/非平衡输运
Key words
GaN HEMT/electron-phonon coupling/Monte Carlo method/temperature effect/non-equilibrium transport
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