In a breakthrough that could revolutionize the energy sector, researchers have developed a novel technique to create ultra-smooth diamond trenches, a critical component for next-generation power devices. The study, led by Masatsugu Nagai of the Advanced Power Electronics Research Center at the National Institute of Advanced Industrial Science and Technology (AIST) in Japan, has been published in the journal ‘Applied Surface Science Advances’ (which translates to ‘Advances in Applied Surface Science’).
The research focuses on trench-type inversion-channel diamond metal-oxide-semiconductor field-effect transistors (MOSFETs), devices that promise to deliver ultra-low power loss. These devices leverage the exceptional properties of diamond, such as its high thermal conductivity and electron mobility, making them ideal for high-power, high-frequency applications. However, the formation of diamond trenches with flat {111} sidewalls—essential for these devices—has been a significant challenge.
Conventional methods often result in macrosteps, or uneven surfaces, on the sidewalls, which can hinder the formation of high-quality MOS interfaces and inversion channels. Nagai and his team tackled this issue by employing a thermochemical etching technique using Ni films in water vapor. Their findings reveal that by carefully controlling the etching temperature, they can suppress macrostep formation and achieve nanoscale-flat {111} sidewalls.
“We found that macrosteps form on the sidewalls at temperatures of 940 °C or higher,” Nagai explained. “However, at lower temperatures, we were able to fabricate sidewalls that were smooth at the nanoscale, without any detectable macrosteps using scanning electron microscopy (SEM).”
The key to this success lies in the extended etching time for the sidewalls at lower temperatures. This discovery provides a fundamental technique for fabricating trench-type inversion-channel diamond MOSFETs, bringing us one step closer to realizing ultra-low-loss power devices.
The implications for the energy sector are substantial. As the world grapples with the need for more efficient and sustainable energy solutions, devices that can operate at high power and high frequency with minimal loss are in high demand. Diamond-based MOSFETs, with their superior material properties, could play a pivotal role in this transition.
“This research is a significant step forward in the development of diamond-based power electronics,” said Nagai. “It opens up new possibilities for high-power, high-frequency applications, from renewable energy systems to electric vehicles and beyond.”
As the energy sector continues to evolve, innovations like this one will be crucial in shaping the future of power generation, transmission, and consumption. With the publication of this study, the path forward for diamond-based power devices has become clearer, offering exciting prospects for the energy sector and beyond.