Seeing more clearly at the nanoscale

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The AlGaN/GaN heterostructure used to fabricate Transphorm’s diodes and transistors. The highelectron-mobility channel is also shown.

integrated into the final module solutions are based on the aluminum gallium nitride (AlGaN)/gallium nitride (GaN) heterostructure fabricated into both diodes and transistors. The transistor is a high-electron-mobility transistor. The cross section of the material structure and the device design of a typical device is shown in the figure. The current is carried by a two-dimensional electron gas

possessing high electron mobility formed at the AlGaN/GaN interface to neutralize the positive charge that exists at the interface due to the polarization difference between the AlGaN and the GaN. This polarization difference (a materials property) increases almost linearly with Al composition enabling a simple tailoring of the electron density by material composition without the need for doping. This results in extremely high electron mobility, in excess of 2000 cm2V−1s−1 with charge densities typically around 1 × 1013cm−2. The resulting low resistance of the channel coupled by the high breakdown voltage enabled by the high breakdown field strength (>3 × 106cm−1; 10 times that of silicon because of the larger bond strength and bandgap of GaN) results in exceptionally high efficiencies of over

99.2% in converting 200 V dc to 400 V dc and 98.5% in a photovoltaic inverter both in the range of a kW of power at a high frequency of 100 kHz. These results demonstrate that the promise of highefficiency GaN-based power conversion is now becoming a reality and the market penetration will continue to increase as the technology matures and the advantages of low-loss and small form factor drive new designs.

Opportunities Transphorm is currently working with and continues to seek to work with companies as customer-partners to help develop new solutions together by combining Transphorm’s expertise with that of the customer. The company also works with universities that have an established expertise in power conversion so that the capabilities of the technology can be studied in innovative new architectures and applications including advanced packaging. Source: Carl Blake, VP Marketing, Transphorm Inc., 115 Castilian Drive, Goleta, CA 93117, USA; tel. 805-456-1300 ext.116; fax 805-968-1985; email [email protected]; and www.transphormusa.com.

force and optical microscopes, surface/ chemical analyzers, and other equipment exceeded $3 billion in 2009. Dune Sciences’ products and services leverage the value of these instruments by maximizing their utility to meet a growing list of application needs in both materials science and life science. In materials science SMART grids standardize sample preparation and provide superior data quality for a wide range of materials for accurate determination of their physical properties (e.g., size and shape), for process optimization and materials integration, manufacturing quality control, failure analysis, and environmental monitoring of nanomaterials to determi