At this week's International Electron Devices Meeting, the nanoelectronics
research center IMEC presents
an innovative, simple and robust GaN-on-Si double heterostructure FET (field
effect transistor) architecture for GaN-on-Si power switching devices. The architecture
meets the normally off requirements of power switching circuits and is characterized
by low leakage and high breakdown voltage, both essential parameters to reduce
the power loss of high-power switching applications.
High-voltage power devices are traditionally based on Si-MOSFET structures.
However, for a number of applications, Si power devices have reached the intrinsic
material limits. GaN-compounds are nowadays the best candidates to replace Si
power devices, thanks to their high band gap (excellent transport properties)
and their high electrical breakdown field. However, the cost of GaN power devices
is high. GaN-epilayers grown on large diameter Si wafers, potentially up to
200mm, offer a lower cost technology compared to other substrates.
Imec obtained a high-breakdown voltage of almost 1000V combined with low on-resistance
by growing an SiN/AlGaN/GaN/AlGaN double heterostructure FET structure on a
Si substrate. By combining its double heterostructure FET architecture with
in-situ SiN grown in the same epitaxial sequence as the III-nitride layers,
imec succeeded in obtaining e-mode device operation. This is typically required
in applications for safety reasons. The fabrication is based on an optimized
process for the selective removal of in-situ SiN. The resulting SiN/AlGaN/GaN/AlGaN
double heterostructure FET is characterized by a high breakdown voltage of 980V,
an excellent uniformity and a low dynamic specific on-resistance of 3.5 mW.cm2
that is well within the present state-of-the-art. These results hold the promise
of a huge market opportunity for GaN-on-Si power devices.
Within imec’s industrial affiliation program (IIAP) on GaN-on-Si technology,
imec and its partners focus on the development of GaN technology for both power
conversion and solid state lighting applications. An important goal of the program
is to lower GaN technology cost by using large-diameter GaN-on-Si and hence
by leveraging on the scale of economics. Imec invites both integrated device
manufacturers and compound semiconductor industry to join the program. Partners
can build on imec’s extensive expertise in GaN and benefit from sharing
of cost, risk and talent.
Imec performs world-leading research in nano-electronics. imec leverages its
scientific knowledge with the innovative power of its global partnerships in
ICT, healthcare and energy. imec delivers industry-relevant technology solutions.
In a unique high-tech environment, its international top talent is committed
to providing the building blocks for a better life in a sustainable society.
Imec is headquartered in Leuven, Belgium, and has offices in Belgium, the Netherlands,
Taiwan, US, China and Japan. Its staff of more than 1,650 people includes over
550 industrial residents and guest researchers. In 2008, imec's revenue (P&L)
was 270 million euro.