High Electron Mobility Transistor (HEMT)

Why is it in News? 

Indian Scientists from Bangalore have developed a highly reliable, High Electron Mobility Transistor (HEMTs) that is normally in the OFF state,  the device and can switch currents up to 4A and operates at 600V.

What is HEMT?

• A high electron mobility transistor or HEMT is a type of field-effect transistor (FET) that is used to produce a high performance at microwave frequencies.
• The HEMT provides a fusion of low noise figure that comes combined with the unique ability to function at very high microwave frequencies.
• These devices are commonly used in aspects of radiofrequency designs that require high performance at high-frequency levels.
• They produce a high gain, which makes these transistors very useful as amplifiers. They can switch speeds very rapidly.
• And, they produce very low noise values as the current variations in these transistors are comparatively low.

What are practical applications of HEMT?

• HEMTs are used in applications where microwave millimetre wave communications are conducted.
• They are also used for radar, imaging, as well as radio astronomy.
• They are also used in voltage converter applications.
• These transistors are also ideal as digital on-off switches in integrated circuits, and to be used as amplifiers for huge amounts of current by using a small voltage as a control signal.

What is the significance?

• This first-ever indigenous HEMT device made from gallium nitride (GaN) is useful in electric cars, locomotives, power transmission and other areas requiring high voltage and high-frequency switching.
• It would reduce the cost of importing such stable and efficient transistors required in power electronics.

How does it work?

• Power electronic systems demand high blocking voltage in OFF-state and high current in ON-state for efficient switching performance.
• Specific transistors called HEMTs made of aluminium gallium nitride/ gallium nitride (AlGaN/GaN) provides an edge over silicon-based transistors as they allow the systems to operate at very high voltages, switch ON and OFF faster, and occupy less space.
• Commercially available AlGaN/GaN HEMTs use techniques to keep the transistor in a normally OFF state, which affects the stability, performance and reliability of the device.
• Therefore, to meet this need, researchers have developed a new kind of HEMT, which is in the OFF state by default and works like any other commonly used power transistor.