Enabling Technology Project
High-Quality and Large-Diameter GaN Wafer
Outline of the area
Specially appointed professor,
In this project, a high-quality and large-diameter GaN wafer is developed to reduce energy and power losses in power devices and LEDs. Specifically, by reducing the crystal defects which affect the electrical property and by enlarging the wafer diameter, mass production and cost-saving of the devices can be possible.
In order to do that, using the Naflux method and point seed method, dislocation-free and non-strained crystals are grown from small seed crystals. In this way, 6-inch GaN wafers can be produced where are 100/cm2 in dislocation defect density and zero/cm2 in screw dislocation defect density. In addition, superior electrical property can be obtained in a diode fabricated thereon, and it was confirmed that the reduction of the crystal defect was extremely effective for the device performance.
Just like in the case of Si semiconductors and compound semiconductors, the substrates with low crystal defect density is indispensable for producing excellent devices. However, it takes a long time and significant cost to produce them.
In this project, higher quality and larger diameter GaN crystal is largely improved upon developing a crystal growing apparatus. Finally, we aim at the mass production of the high quality 8-inches or more GaN wafer and low power loss devices and LEDs.
Over 8-inch large-Diameter GaN Wafers for Energy-Saving Devices
Professor, Osaka University
Our group promotes crystal growth of GaN with large diameter and low crystal defects. High quality GaN crystals are expected for power devices and LED substrate. Combination of the Naflux method and the point seed method, which is our new technique, achieved the production of GaN wafer with 100/cm2 in dislocation defect density and 6 inches in diameter. Our next goal is development of lowcost technology for producing 8 inches GaN wafers with comparable quality of Si wafers.
High Frequency GaN Power Module System Integration
Professor, ISIR, Osaka University
GaN power devices are expected to reduce the loss in electric energy conversion at the same time of shrinkage of module size by high frequency. Currently, the bottle neck is in the luck of heat resistant packaging beyond 200 ºC. Here we break through this issue by Ag sinter joining and maximize the GaN potential for the next generation of power devices. The developed thermal stress relaxation, non-destractive inspection and noise reduction technology with the aid of basic science and simulation will open a opportunity for the wide application of GaN power devices.