Indian Scientists Develop Indigenous Normally OFF High Electron Mobility Transistor

Context

Indian scientists have developed a highly reliable, High Electron Mobility Transistor (HEMTs) which are required in power electronics applications.

A high-electron-mobility transistor (HEMT), also known as heterostructure FET (HFET) or modulation-doped FET (MODFET).
- It is a field-effect transistor incorporating a junction between two materials with different bandgaps as the channel instead of a doped region.
- A commonly used material combination is GaAs with AlGaAs.
- Since GaAs has higher electron affinity, free electrons in the AlGaAs layer are transferred to the undopedGaAs layer where they form a two-dimensional high mobility electron gas within (10 nm) of the interface.

Applications

These are similar to those of MESFETs – microwave and millimetre wave communications, imaging, radar, and radio astronomy – any application where high gain and low noise at high frequencies are required.
Gallium nitride HEMTs on silicon substrates are used as power switching transistors for voltage converter applications.

The HEMT is a normally OFF device.
- It can switch currents up to 4 Ampere and operates at 600 Volts.
- This first-ever indigenous HEMT device is made from gallium nitride (GaN).
Application: It is useful in electric cars, locomotives, power transmission and other areas requiring high voltage and high-frequency switching.
- 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.
- The developed technology is a first of its kind, which uses a type of chemical called ternary oxide (composed of two different metal ions combined in an oxide matrix or Al, Ti and O), which behaves like material having a larger positive charge concentration (p-type material).
Significance:It does away with intrinsic reliability and performance issues of the in-use industrial techniques for e-mode HEMTs, allowing the development of efficient power switching systems.
- This device will now be taken up for the prototype development and field-testing level.
- With a growing market for electric vehicles in India, such an indigenous development can make India self-reliant for transistor technology, the statement said.