A Novel High-Breakdown-Voltage SOI MESFET by Modified Charge Distribution

Abstract

In this paper, a novel silicon-on-insulator (SOI) metal-semiconductor field-effect transistor (MESFET) with modified charge distribution is presented. Changing charge distribution leads to lower electric field crowding and increased breakdown voltage ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">BR</sub> ). For modifying charge distribution, a metal region (MR) is utilized in buried oxide of the SOI MESFET. In order to achieve the best results, the MR location and dimensions are optimized carefully. DC and radio frequency characteristics of the SOI MESFET with MR (MR-SOI MESFET) are analyzed by 2-D numerical simulation and compared with conventional SOI MESFET (C-SOI MESFET) characteristics. The simulated results show that the MR has excellent effect on the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">BR</sub> of the device. The <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">BR</sub> of the MR-SOI MESFET structure improves by 116% compared with that of the C-SOI MESFET structure. Although drain current of the proposed structure reduces slightly, 126% improvement in maximum output power density of the device is achieved due to high enhancement of the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">BR</sub> . Also, the MR leads to the enhancement of maximum oscillation frequency and maximum available gain of the MR-SOI MESFET structure. As a result, the MR-SOI MESFET structure has superior electrical performances in comparison with the similar device based on the conventional structure.