Southbound SET Marks a Trail of University Research

Sensor Electronic Technology, Inc. (SET; Latham, NY), is developing and commercializing advanced electronic devices based on wide bandgap semiconductors as a result of funding over the past several years through MDA's advanced tech-nology and SBIR programs.
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Aside from increasing power levels and reducing the size of MDA's radar systems, wide bandgap materials can serve as an improvement for a host of commercial applications ranging from wireless communications to medical detection. They can also be used to make white light-emitting diodes-an important enabler that could revolutionize the entire lighting industry by replacing existing incandescent and fluorescent lighting with a brighter and far more energy efficient alternative. One study suggested that white LEDs, if fully implemented, would save up to $115 billion per year in electricity by year 2015, thus reducing air pollution and other waste generated from power plants.

With much potential and so many benefits, several companies and research institutes have worked in this area since the mid-1980s (depending on where and when you start counting), especially in the area of silicon carbide and more recently, gallium nitride. The material system that SET focuses on is aluminum indium gallium nitride (AlInGaN). Using a patent-pending process called pulsed atomic layer epitaxy (PALE), the company is fabricating this material into devices called metal oxide semiconducting heterostructure field effect transistors or MOSHFETs.

While PALE-fabbed AlInGaN MOSHFETs sound a lot like alphabet soup, the devices address many of the problems that researchers working in wide bandgap semiconduc-tors are grappling with today.

"At present, nearly all the development work has focused on conventional high electron mobility transistor (HEMT) devices on sapphire and insulating silicon carbide substrates. But several key problems impede commercial development of these devices, such as gate leakage and current collapse, which reduces radio frequency power capacity," explained Dr. Remis Gaska, SET's president.

By using PALE to deposit AlInGaN, the researchers can pulse the material into the system, layer by layer, thus forming a high-quality heterointerface between the various layers of the device. Owing to the deposited silicon dioxide layer, gate leakage is reduced by four to six orders of magnitude, saturation current goes up, and DC and RF characteristics stay the same as, or are even better than, those for conventional HFETs. SET has initiated another Phase I MDA SBIR contract to develop a double heterostructure field-effect transistor to address current collapse. By combining the two technologies, the company will be able to make devices that address gate leakage and current collapse. Initial testing this March provided very promising results.

The 10-employee SET is southbound to Columbia, SC, to be with its university collaborator, Dr. Asif Khan at the University of South Carolina. (The company originally spun out as a result of research conducted by Dr. Michael Shur at Rensselaer Polytechnic Institute.) SET is pursuing three key commercial areas: (1) RF electronics for radar and wireless communications, such as ultra-high power base stations and satellite communications; (2) ultraviolet light emitters for bio-agent detection, biomedicine, and water purification systems; and (3) solid-state lighting. "Our fully vertically integrated material growth/ device fabrication facility buildup is in progress in Columbia and most of SET operations are expected to be transferred this fall," said Dr. Gaska. "Our goal is to become a major supplier of materials and devices for emerging high-power RF electronic, visible-ultraviolet optoelectronic, and solid-state lighting markets." SET is looking for future investment in the technology at its facilities in South Carolina.

-L. Aitcheson