Normally-off GaN HV-Transistors for Power Electronics
Transistor gate made of p-type GaN with metallization on top
Flip-chip mounted 50 A / 250 V GaN power transistor
FBH successfully developed gallium nitride (GaN) power transistors offering up to 1000 V breakdown strength. An additional advantage is their normally-off characteristic. Due to safety reasons, the transistor can only be opened by applying a positive gate voltage of more than 1 V, which is a precondition for use in power electronics.
The newly developed gate module made of p-type GaN causes the required normally-off characteristic. The high breakdown strength was obtained by increasing the confinement of the transistor channel.
Because of its high band gap and breakdown strength, gallium nitride as semiconductor material has advantages compared to silicon for power electronics. GaN transistors can be operated at higher temperatures, higher voltages and higher current densities than silicon devices of the same size. Hence, less power losses appear and lower parasitic capacitances and better electron transport properties lead to faster switching speed. Converter modules can thus become smaller. Due to the higher possible operating temperature, cooling efforts scale down, weight and size of the converter modules further decrease. For an electrically powered car, this leads to a significant energy saving.
Power converters based on GaN transistors may thus offer a higher efficiency compared to Si-based systems. They are more robust, faster and more efficient and thus highly attractive for industry.
FBH research: 03.08.2010