IISc team's new power switch to enable high-speed charging for vehicles, phones

The Indian Institute of Science (IISc) has indigenously developed a power switch that will increase the efficiency of chargers for electric vehicles, phones and laptops. It will also make space and military applications like radar more potent.

This new development is a gallium nitride (GaN) power switch that will help efficiency in power converters and wireless communications.

These high-performance GaN transistors are seen as a potential replacement for traditional silicon-based ones, and will serve as building blocks in electronic devices, including the ultra-fast chargers for vehicles and electronic gadgets as well as radars in military and space applications.

A study on the development of the switch was published in the journal, Microelectronic Engineering. The IISc said the switch was fully developed at its Centre for Nano Science and Engineering (CeNSE).

Digbijoy Nath, Associate Professor at CeNSE and corresponding author of the study, said the “very promising and disruptive technology” depended on materials and devices that are heavily import-restricted.

India does not have GaN wafer production capability at a commercial scale and the manufacturing know-how is also a heavily guarded secret, Nath said. “This is essentially a demonstration of the indigenous GaN technology development,” he said.

To design the GaN power switch, the team used a metal organic chemical vapour deposition technique, developed over a decade in the lab of Srinivasan Raghavan, Professor and Chair, CeNSE. The technique involves growing GaN alloy crystals layer by layer on a two-inch silicon wafer to fabricate a multi-layered transistor.

The team took the help of Kaushik Basu, Associate Professor in the Department of Electrical Engineering, and his lab, to build an electrical circuit, using these transistors, and test their switching performance.

GaN transistors are, typically, switched on all the time, unless a negative voltage turns them off. Power switches in chargers and adapters, however, need to be switched off and turned on only with positive voltage. To achieve this operation, the researchers combined the GaN transistor with a commercially available silicon transistor, and kept the device normally off.

Rijo Baby, PhD student at CeNSE and first author of the study, said the packaging of the device was also indigenously developed. The researchers found the device’s performance comparable to state-of-the-art switches available commercially, with a switching time of about 50 nanoseconds between on and off operations.

What is gallium nitride? 

Gallium nitride (GaN) is a very hard, mechanically stable wide bandgap semiconductor. With higher breakdown strength, faster switching speed, higher thermal conductivity and lower on-resistance, power devices based on GaN significantly outperform silicon-based devices. Gallium nitride crystals can be grown on a variety of substrates, including sapphire, silicon carbide (SiC), and silicon (Si). (Source: Internet)