The technology to laminate thin gallium nitride films on a silicone or sapphire substrate to build a gallium nitride semiconductor is widespread at the present stage. Quality is important because different kinds of materials are laminated, and reliability is significant because a power semiconductor requires resistance against high current. This is why a gallium nitride semiconductor is not used for power semiconductors. A gallium nitride power semiconductor loses less energy than the existing silicon power semiconductor, but its resistance increases in high voltage operation. Rohm opened up the road to the practical application of a gallium nitride power semiconductor by controlling this phenomenon. The company will ship samples to prospective customers shortly to improve high-frequency power source and address measures against noise with them to achieve a higher than 1 MHz switching frequency.
The technology to build a substrate entirely of gallium nitride is also being developed. However, it costs too much to build a gallium nitride substrate at present. The production cost of a gallium nitride substrate of 2 inch in diameter is 100,000-150,000 yen that is 50 times higher than a sapphire substrate used for LEDs. However, Sumitomo Electric, the dominant producer of gallium nitride substrates, will increase the diameter of its products from 2 inches to 6 inches, and Mitsubishi Chemical plans to increase the production capacity of gallium nitride substrates to reduce the price to one tenth. Building the foundation to expand the gallium nitride semiconductor market is in progress.