Science & Technology (Commonwealth Union) – Scientists at Indian Institute of Science (IISc) have demonstrated key principles for engineering gallium nitride (GaN) power transistors, improving their safety and making them more practical for advanced electronics like electric vehicles and large-scale data centres.
As digitalization rapidly expands, energy conservation and its impact on the environment have become a key focus due to the possibility of a rapid increase in energy consumption.
GaN technology can sharply lower energy wastage and shrink the size of power converters and related electronics to roughly a third of their usual dimensions. However, widespread use has been hindered by limitations in the gate component that regulates current flow. In today’s commercial devices that rely on a p-GaN gate, conduction begins at a relatively low threshold voltage — generally about 1.5 to 2 volts. These transistors also tend to leak current once the voltage rises beyond about 5–6 volts.
Until now, researchers lacked a deep theoretical understanding of how gate control actually governs transistor behaviour and what precisely sets the threshold voltage. A team from the Department of Electronic Systems Engineering at IISc addressed this gap through a two-stage investigation designed to analyse these underlying mechanisms.
“What is unique here is the two-step approach: we first established the missing physics link between p GaN depletion state, leakage pathways, and turning on, and then used that understanding to engineer a new gate stack that delivers a much more ‘MOSFET-like’ gate behaviour,” explained Mayank Shrivastava, who is Professor and Chair at ESE and corresponding author of the studies.
In the first phase, the IISc researchers created several new gate designs and linked electrical test results with modelling and microscopy studies. They found that the device’s performance changes depending on whether the p-GaN layer is fully depleted or only partly depleted. In the partially depleted state, extremely small leakage channels determine how the device behaves: when positive charge builds up at a key interface, the device switches on prematurely; when that buildup is prevented, depletion spreads further first, causing the transistor to activate later at a higher threshold. Shrivastava noted that it was unexpected how much influence these minor leakage paths have over the overall turn-on behaviour.
Building on these findings, the team engineered and demonstrated new metal-based gate stacks capable of reducing gate leakage by as much as 10,000 times. At the same time, the design improves threshold stability and achieves gate breakdown voltages of roughly 15.5 V.
In the second phase, the researchers converted their fundamental discoveries into a fully integrated AlTiO (aluminium–titanium oxide) p-GaN gate stack — an entirely new, patented architecture. This design blocks unwanted charge injection and enforces a high-threshold, depletion-extension operating mode. Devices built with this approach reach ultrahigh threshold voltages above 4 V, approaching the range of silicon-based MOSFETs, while preserving strong gate control, enhancing threshold reliability, and delivering extremely high gate breakdown performance. According to lead author Rasik Rashid Malik, a PhD student at ESE, this advancement could accelerate the adoption of GaN technology in electric vehicle power systems, server and data-centre supplies, renewable energy inverters, and other demanding high-power switching uses.
These improvements could accelerate the adoption of GaN systems in fields that demand high reliability, durability, and strong performance tolerances, while creating homegrown opportunities to jump ahead in delivering cutting-edge electronic solutions.
The group is now aiming to expand the technology toward commercial rollout by leveraging government backing, industrial licensing agreements, and strategic partnerships.
“Achieving a higher threshold voltage together with low leakage and robust gate overdrive margin is one of the key enablers for GaN’s next phase of adoption,” added Shrivastava. “That is exactly what we set out to solve.”
