Toyoda Gosei achieves state?of?the?art high current operation with vertical GaN power semiconductor

Toyoda Gosei has achieved state-of-the-art high current operation (1) in a vertical GaN power semiconductor developed using gallium nitride (GaN), a main material in blue LEDs. Power semiconductors are widely used in power converters (2) such as power sources and adaptors for electronic devices. However, simultaneous achievement of both high breakdown voltage (3) and low loss (4) (low conduction loss and switching loss) at high levels has been difficult with conventional silicon due to its material properties.

In its power semiconductors, Toyoda Gosei uses GaN, which has material properties of high breakdown voltage and low loss, and employs a vertical device structure in which electrical current flows vertically from or to a substrate. These changes have enabled a GaN power transistor chip with operating current of over 50A, highest ever reported for vertical GaN transistors (2), and high-frequency (several megahertz) operation. Some prospective applications are shown below.

Toyoda Gosei will continue development of these power semiconductors for improved reliability, aiming to achieve practical applications in cooperation with semiconductor and electronics manufacturers.

The newly developed vertical GaN power transistors (MOSFET) (5) and Schottky barrier diodes (6) will be presented on panel displays at the Techno-Frontier 2018 Advanced Electronic & Mechatronic Devices and Components Exhibition, held at Makuhari Messe, Chiba, Japan from April 18 to April 20. The world’s first full vertical-GaN DC-DC converter equipped with these devices will also be demonstrated.

(1) According to internal Toyoda Gosei survey (as of April 2018).
(2) Power conversion refers to conversion between direct and alternating current, direct current transformation, alternating current frequency conversion, etc.
(3) The property of withstanding the high breakdown voltage during power conversion and not allowing current flow during off operation (non-conductance).
(4) Heat loss generated by electrical resistance during electric conduction or when switching on/off.
(5) Semiconductor used in power on/off. MOSFET: Metal-oxide-semiconductor field-effect-transistor.
(6) Semiconductor used in converting (rectification) from alternating current to direct current. Toyoda Gosei uses a trench MOS structure, in which trenches are formed at fixed intervals in the chip surface of the diode, achieving low leakage current operation at high temperatures.