High Performance 4H-SiC Optically Controlled MOS Transistor

TL;DR

This paper presents an optically controlled 4H-SiC MOSFET that uses ultraviolet light for switching, offering high on/off ratios, fast response times, and improved reliability over traditional voltage-driven devices.

Contribution

The study introduces a novel optically controlled SiC MOSFET with direct optical modulation, bypassing gate-oxide issues and EMI susceptibility of conventional devices.

Findings

Achieves an on/off current ratio over 10^6 under UV illumination.

Demonstrates a rise time of 1.44 ns for fast switching.

Photogenerated current exceeds that of a 15 V gate bias at low optical power density.

Abstract

This paper introduces an optically controlled 4H-SiC MOSFET designed to avoid the gate-oxide interface unreliability and electromagnetic interference (EMI) susceptibility inherent in conventional voltage-driven devices. By replacing the conventional gate electrode with a semi-transparent optical window, the device enables direct modulation of channel conductivity through ultraviolet illumination. Electrical and optical characterization demonstrates that under an optical power density above 0.1 W/cm^2, the device achieves an on/off current ratio exceeding 10^6 between illuminated and dark states. Notably, at an optical power density of 0.031 W/cm^2, the photogenerated current density exceeds that obtained under a gate bias of 15 V in magnitude. Energy band analysis confirms that the optical switching mechanism operates through direct photogenerated carrier generation and transport, fundamentally differing from conventional gate voltage control and thus circumventing interface-trap and EMI-related limitations. Dynamic measurements further reveal fast switching capability, with a rise time of 1.44 ns. These results validate the feasibility of optically driven switching in SiC-based devices and highlight their potential for high-speed logic applications.