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GaN Doping through Transmutation Processing

University of Missouri

High quality GaN FETs through Transmutation Doping and Low Temperature Processing

Program: 
ARPA-E Award: 
$499,999
Location: 
Columbia, MO
Project Term: 
09/20/2017 to 03/19/2020
Project Status: 
ACTIVE
Technical Categories: 
Critical Need: 

Electricity generation currently accounts for ~40% of primary energy consumption in the U.S. and continues to be the fastest growing form of end-use energy. Power electronics are responsible for controlling and converting electrical power to provide optimal conditions for transmission, distribution, and load-side consumption. By 2030 as much as 80% of all electricity could pass through some form of power electronics. Applications for power electronics are widespread and include uses in power supplies, motor drives, grid applications, data centers, and distributed energy resources. Today, most power electronics are based on silicon semiconductor devices that have reached their efficiency limits at high power and frequency, due to the material limitations of silicon. Wide-bandgap (WBG) semiconductors such as gallium nitride (GaN) have superior electrical conductivity, breakdown properties, and switching speed. This allows for power converters with much improved efficiencies over silicon - while also dramatically reducing system size, weight, and form factor. Power semiconductor devices overwhelmingly use vertical architectures to realize high breakdown voltage (>1200V) and current levels, without having to enlarge chip size. The vertical architectures require the ability to add specific impurities to selected regions of a semiconductor to produce negative (n-type) and positive (p-type) electrical conduction, a process called doping. Currently, no doping process exists to form selective p-type regions in GaN. This is the major barrier to realization of GaN based vertical power electronic devices. The development of a selective p-type doping process will enable vertical GaN device architectures and unlock the potential of using the WBG semiconductor GaN in power electronics.

Project Innovation + Advantages: 

The University of Missouri will develop neutron transmutation doping of GaN to fabricate uniform heavily doped n-type GaN wafers. GaN has long been proposed as a superior material for power electronic devices due to the intrinsic material advantages such as greater breakdown voltages and greater stability. Unfortunately, the fabrication of GaN wafers with uniform and high levels of dopants is challenging due to a lack of sufficient control during the existing crystal growth methods. The neutron transmutation doping process, which consists of exposing GaN wafers to neutron radiation to create a stable network of the dopant germanium within the GaN wafer, allows for a greater degree of precision and results in a high level, uniform doping concentrations across the wafer. With this method, repeatable production of high quality GaN substrates may be achieved. Specific innovations in this proposal concern an in-depth study of neutron transmission doping and a characterization of the resulting wafer, including analyzing resistivity, dopant concentration, unwanted impurities, and damage to the GaN lattice.

Potential Impact: 

If successful, PNDIODES projects will enable further development of a new class of power converters suitable in a broad range of application areas including automotive, industrial, residential, transportation (rail & ship), aerospace, and utilities.

Security: 

More energy efficient power electronics could improve the efficiency of the U.S. power sector. They could also significantly improve the reliability and security of the electrical grid.

Environment: 

More efficient power use may help reduce power-related emissions. Low-cost and highly efficient power electronics could also lead to increased adoption of electric vehicles and greater integration of renewable power sources.

Economy: 

Improved power electronics could yield a significant reduction in U.S. electricity consumption, saving American families and businesses money on their power bills.

Contacts
ARPA-E Program Director: 
Dr. Isik Kizilyalli
Project Contact: 
Prof. Jae Kwon
Release Date: 
6/14/2017