Improvement of the Self-Heating Performance of an Advanced SiGe HBT Transistor Through the Peltier Effect

Abstract

This article focuses on the reduction of the self-heating (SH) effect in an advanced SiGe hetero-junction bipolar transistor (HBT) considering the Peltier effect. Bismuth Telluride is the working material for most Peltier cooling devices and thermoelectric (TE) generators. This is because Bi <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Te <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> has the highest TE figure of merit (ZT), of any material around room temperature. An electro-thermal model is performed using the COMSOL multiphysics software. Accurate direct current (dc) and radio frequency (RF) electrical simulations, as well as the extraction of the device static and dynamic thermal parameters are performed on the proposed structure. The current gain ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula> ), the cutoff frequencies ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${f}_{max}$ </tex-math></inline-formula> ), and the maximum network temperature <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${T}_{max}$ </tex-math></inline-formula> have been considered. We have extracted these parameters by taking into account the phenomenon of the SH which occurs in this device. We then have integrated around the structure, a cooling system considering elements with “Peltier effect.” So, in this case, the electrothermal model is essentially based on the Peltier effect. It allows generating a potential <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta {V}$ </tex-math></inline-formula> difference from a temperature <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta {T}$ </tex-math></inline-formula> gradient in the considered structure. Thus, we analyze carefully the heat distribution and the electrical potential on the surface of the component. By using this cooling method, we can observe clearly a decrease in the maximum temperature ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${T}_{max}$ </tex-math></inline-formula> ) of the HBT SiGe due to the SH phenomenon: from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${T}_{max} =467$ </tex-math></inline-formula> K to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${T}_{max}=330$ </tex-math></inline-formula> K. The proposed method shows a sensible improvement of dc and RF figures considering the thermal impact of Peltier effect upon the transistor.