An Improved 4H-SiCMESFET with Un-Doped and Recessed Area under the Gate for High Power Applications
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ORIGINAL PAPER
An Improved 4H-SiCMESFET with Un-Doped and Recessed Area under the Gate for High Power Applications S. M. Razavi 1 Received: 16 June 2020 / Accepted: 7 September 2020 # Springer Nature B.V. 2020
Abstract In this work, a new structure of 4H-SiC MESFET with un-doped and recessed region under the gate (UR-MESFET) is reported. Channel of the proposed device is recessed into the p-buffer layer. The length and thickness of the un-doped area is equal to those of the recessed section. The un-doped section reduces peak electric field in the channel and then postpones breakdown phenomena. This can enhance breakdown voltage. Maximum breakdown voltage of the suggested transistor is about 138 V. This value is about 19% larger than that in the conventional (116 V). Recessed channel to the p-buffer increases saturated drain current significantly. Obtained results illustrate that saturated drain current of UR-MESFET is about 50% higher than that of the conventional device. Also, increasing breakdown voltage and drain current in the proposed device improves output power density about 90% compared to that in the conventional device. The suggested structure also reduces the gate-source and gate-drain capacitors significantly. The proposed transistor at best reduces the gate-source capacitor by 55% and reduces the gate-drain capacitor by 20% compared to the conventional structure. This makes the transistor perform better at high frequencies. As a result, it can be said that the proposed structure has better performance at high power and frequency than that of the conventional transistor. Keywords 4H-SiC MESFET . Breakdown voltage . Drain current . Output power density . Gate capacitances
1 Introduction As an excellent semiconductor, silicon carbide (SiC) has special electrical properties such as high electron saturation velocity, good thermal conductivity and high critical electric field [1–6]. Due to these excellent properties, metalsemiconductor field-effect transistors based on SiC are one of the most important transistors in high-power and highfrequency applications. They offer wider bandwidth operation and lower system size than Si and GaAs based on MESFET technologies. Hence, MESFET transistors are widely used in high speed and low noise systems. Also, these transistors are very attractive in space and aeronautics applications [7–10]. Due to the lack of gate oxide in SiC-MESFET, these transistors do not have problems such as damaging effects due to radiation plasma and hot carrier effects. In addition, the channel * S. M. Razavi [email protected] 1
Department of electrical engineering, University of Neyshabur, Neyshabur, Iran
in the MOSFET transistors is caused by the inversion layer phenomenon, which greatly reduces the mobility and thus the operating frequency of these transistors. While in the MESFET transistors, the channel is formed at the bottom of the active area, which increases the mobility of the carriers in these transistors. This is one of the most important advantages of MESFET transistors o
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