In a major breakthrough, scientists from the Indian Institute of Science Bangalore (IISc) have developed the first-ever indigenous High Electron Mobility Transistor (HEMTs), made from gallium nitride (GaN), for use in electric cars, locomotives and power transmission, the ministry of science and technology said on Thursday.

Until now the country was completely dependent on imports for such stable and efficient transistors required in power electronics and the development comes as a major success for the ‘Make in India’ campaign, the government statement said. 

The new HEMT device enables high voltage and high-frequency switching. It is a normally OFF device and can switch currents up to 4A and operates at 600V.

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) provide 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.

$5 billion market seen by 2020

The overall power device market is projected to cross the $18 billion mark by 2020, out of which the market for HEMTs is projected to cross the $5 billion market. So, GaN HEMTs will acquire a major share of the power device market. With a growing market for electric vehicles in India, such an indigenous development can make India self-reliant for transistor technology, the statement added.

Commercially available AlGaN/GaN HEMTs use techniques to keep the transistor in normally OFF state, which affects the stability, performance and reliability of the device.

Therefore, to meet this need, Prof. Mayank Shrivastava, Dept. of Electronic Systems Engineering, his co-investigators Prof. G. Narayanan, Prof. Digbijoy Nath, Prof. Srinivasan Raghavan and Prof. Navakanta Bhat, from Department of Electrical Engineering, and Centre for Nanoscience & Engineering, and their students, all from Indian Institute of Science Bangalore (IISc), have developed the new kind of HEMT, which is in the OFF state by default and works like any other commonly used power transistor, the official statement said.  

This device will now be taken up for the prototype development and field-testing level (TRL 5). The scientists used aluminium titanium oxide as the gate oxide, where the percentage of aluminium could be controlled during the fabrication process. Since aluminium titanium oxide is stable, it resulted in high reliability of the transistor.