Product category:
Discrete Power Devices
News Release from: Oki Electric | Subject: GaN-HEMT
Edited by the Electronicstalk Editorial
Team on 18 October 2005
Novel transistor design cuts
amplification costs
Oki Electric has developed a power transistor with dramatically improved amplifying characteristics.
Oki Electric has developed a power transistor with dramatically improved amplifying characteristics This gallium nitride high electron mobility transistor (GaN-HEMT), is formed on a large diameter silicon substrate achieving a world record for transconductance rating of 350mS/mm and maximum oscillation frequency (fmax) of 115GHz
This article was originally published on Electronicstalk on 10 Apr 2002 at 8.00am (UK)
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Because this GaN-HEMT is achieved on a silicon wafer - not on conventional SiC (silicon carbide) - it can reduce costs by approximately 50%.
This will help wireless communication systems become lower power consumption, smaller and lower cost.
"Succeeding in improving amplifying characteristics for power transistors is an exciting achievement for Oki, as the market has been in need of smaller and lower power consumption wireless communication systems", said Harushige Sugimoto, Senior Vice President and Chief Technology Officer of Oki Electric.
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"By enhancing higher output of transistors based on this technology, we can contribute to the acceleration of WiMAX and next generation wireless communication systems".
"Volume shipment of such products are planned to start from 2007".
In addition to a 115GHz figure for fmax and 350mS/mm figure for transconductance, which is an indicator of amplification performance, the transistor achieved a 56GHz current gain cutoff frequency.
This is a significant improvement from previous GaN-HEMT on silicon substrate devices, which had a range of 70 to 80GHz fmax, and achieves a performance equivalent to GaN-HEMT on SiC substrates.
Conventionally, power transistors using GaN were developed on a SiC substrate due to its advantage of easy crystal growth.
However, there have been problems with SiC boards for its low quality, difficulty to shift to larger diameters, and expensive substrate costs.
The newly developed device is a high electron mobility transistor (HEMT), which grows the AlGaN/ GaN structure on the silicon substrate with very few defects and is fifty to a hundred times lower cost than SiC.
By improving the crystal growth technology for gallium nitride on silicon substrate, Oki was able to gain high electron mobility in a high-quality thin film.
Oki achieved such high ratings by developing a technology to form the gate electrode on a recessed structure, reducing gate length to 0.2um, developing a recessed structure for the ohmic electrodes and optimising the device structure.
This device was jointly developed with the Research centre for Micro-Structure Devices at the Nagoya Institute of Technology, and with support from The Research Promotion Bureau of Japan's Ministry of Education, Culture, Sports, Science and Technology.
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