Power Electronics ♦ news digest
highly competitive business, the balance between change and stability is a critical success factor. Dr. Ploss masters this balance. His appointment preserves continuity. The Supervisory Board firmly believes that he, together with his fellow board members Dominik Asam and Arunjai Mittal, will carry on with Infineon’s successful strategy.”
Bauer began his career in 1985 at Siemens Semiconductors, which was eventually carved-out into Infineon Technologies AG. He was already part of the Management Board when Infineon went public in 2000 and, in 2008, became the company’s CEO. Under his leadership, Infineon executed an extremely successful restructuring and refinancing program in response to the 2009 financial crisis and decisively focused its strategy on profitable growth in the areas of Energy Efficiency, Mobility and Security.
Reinhard Ploss has been with the company for over 25 years and presides over much knowledge of the complex semiconductor industry. After numerous leadership roles in development and manufacturing, he assumed responsibility for Infineon’s Automotive and Industrial units, encompassing products underlying many of Infineon’s sales today. Ploss was appointed to the Infineon Management Board in 2007.
How to cool high-power GaN semiconductor devices
Latest developments in gallium nitride will be used in wireless applications, traffic lights and electric cars A group of researchers at the University of California, Riverside Bourns College of Engineering have developed a technique to keep cool a semiconductor material used in everything from traffic lights to electric cars. GaN semiconductor materials have been used in bright lights since the 1990s, and are now used in wireless applications due to high efficiency and high voltage operation. However, the applications and market share of GaN electronics is limited because it is difficult to remove heat from them. That could change due to a technique developed by the Nano-Device Laboratory research group led by Alexander Balandin, professor of electrical engineering and founding chair of Materials Science and Engineering
program. The research group demonstrated that hot spots in GaN transistors can be lowered by as much 200C through the introduction of alternative heat-escaping channels implemented with graphene multilayers, which are excellent heat conductors. The temperature reduction translates to an increase in the lifetime of the device by a factor of ten. “This represents a transformative change in thermal management,” Balandin says. The new approach to thermal management of power electronics with graphene was outlined in a paper “Graphene quilts for thermal management of high- power GaN transistors” that was published on May 8thin Nature Communications.
Clockwise from top left: optical microscopy image of the high-power GaN heterostructure field-effect transistor (HFET); schematic of the graphene- graphite quilt on top of the transistor structure for spreading the heat from the local hot spot near the transistor drain; coloured SEM image of the graphene quilt overlapping transistor; optical microscopy image of the graphene quilt on the device electrode illustrating its flexibility GaN transistors have been commercially available since 2006.
The problem with them, like all high power operating devices, is the significant amount of dissipated heat, which has to be fast and efficiently removed. Various thermal management solutions such as flip- chip bonding or composite substrates have been attempted. However, applications have still been limited because of increases in temperature due to dissipated heat. The breakthrough in thermal management of GaN power transistors was achieved by Balandin and three of his electrical engineering graduate students: Guanxiong Liu, Zhong Yan, and Javed Khan, who started working at Intel Corporation this year. Balandin has previously discovered that graphene is an excellent heat conductor.
June 2012
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