A Simple Proposal to Reduce Self-heating Effect in SOI MOSFETs
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ORIGINAL PAPER
A Simple Proposal to Reduce Self-heating Effect in SOI MOSFETs Hasan Ghasemi 1 & Mohammad Hazhir Mozaffari 1 Received: 23 February 2020 / Accepted: 12 October 2020 # Springer Nature B.V. 2020
Abstract In this work, we aim to design a silicon on insulator MOSFET in which the self-heating effect is fully removed. Within the proposed scheme, a T-shaped 4H-SiC region is embedded in the buried oxide layer, extended from the silicon drift region towards the substrate providing a heating pathway to improve the low thermal conductivity of the oxide. This T-shaped 4H-SiC part can absorb heat from the active region and transfer it to the substrate area. Therefore, heat dissipation rising from the high gate and drain bias in MOSFETs are reduced. Simulations show that in addition to the maximum lattice temperature that is brought from ~ 694 K to ~ 366 K, DC and AC characteristics of the device have also improved drastically. The proposed transistor demonstrates lower negative differential resistance, more carrier mobility, higher saturation current, higher DC Transconductance, less delay time, and higher cut-off frequency compared to conventional silicon on insulator MOSFET. These promising properties and competitive advantages propose the designed device as a reliable alternative for conventional MOSFETs in high power and RF applications. Keywords SOI MOSFET . Self-heating effect . Lattice temperature . Delay time . Carrier's mobility
1 Introduction Silicon on insulator (SOI) technology is quite recently being considered a promising technology in the very-large-scale integration (VLSI) circuits because of its advantages over other technologies including lower parasitic capacitances, higher switching speed, and lower leakage current. SOI metal oxide semiconductor field-effect transistors (SOI MOSFETs) are one of the most relevant transistors based on SOI technology that exposing some useful characteristics which come from using oxide for isolation. SOI has such advantages over other technologies as immunity against radiations, speed, density and leakage currents, and so forth [1]. When the transistor is in on-state, the produced heat at the active region will not easily reach the substrate and exit the device. The use of a buried oxide (BOX) layer leads to larger heat spreading impedance which then translates into more heat retention. Since it is confined between the sidewall oxide layers and the BOX layer, hence the temperature is raised, and consequently, the device performance is affected in a * Mohammad Hazhir Mozaffari [email protected] 1
Department of Electrical Engineering, Sanandaj Branch, Islamic Azad University, Sanandaj, Iran
destructive manner. This effect which leads to heat accumulation in the drift region is mainly caused by poor heat conductivity of the insulator in comparison to that of the silicon. Even though the presence of a BOX layer is the main difference between SOI and bulk technology, it also provides some features. However, this layer includes a disadvantage too, known as
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