What we learned from ISPSD 2018

Back in 1987 I was leaving school and going off to University meanwhile in Philadelphia there was assembled a collection of global experts on a relatively new category of devices Power Semiconductors.

Reading through the paper titles from that very first meeting the themes are common to those found today, namely innovative ways of designing, manufacturing and testing devices to obtain the very best performance. Why is this important and why has it been going on for 30 years? Well, it’s vital in order to improve the transfer and utilisation of electrical power that make today’s world possible. Power Semiconductors are the very heart of power management in today’s connected world and the 30 years? Constant innovation is improving the efficiency of devices, which has an incredible real world impact; an excellent illustration is from a US DOE report a 1% improvement in efficiency of power supplies to the global IT industry equates to not having to build 5 nuclear power plants. So all these engineers and scientists working on improving the devices are not only allowing new technology such as Electric Vehicles to flourish but also reducing the environmental impact of making and using the power. Solar power for example would be much less efficient without the devices to transfer the electricity from where it is created, (often remote sunny sites) to where it is used (often much less sunny sites like my house).

Interestingly for me was in this year’s conference the plenary talks were shared: one looking at Si devices and one showcasing wide band gap (WBG) devices. Si devices are the backbone of the power semiconductor industry and their performance and sophistication has improved constantly. However, the technology is now coming close to the fundamental limits of Si and new materials are being used in new devices, mainly SiC and GaN now but in the future who knows maybe Diamond and Ga₂O₃ will have a place as well. SiC and GaN have some properties such as electron mobility, band gap and thermal conductivity which make them ideal for high power and high frequency devices. These materials are exciting with massive potential but, and I think some of the engineers at the conference like this, have difficulties in processing and unknowns in behaviour. So the conference had some great papers on device design, modelling and processing of new WBG devices. A common issue was dynamic Ron for GaN devices, this is where the resistance of the device changes as it is operated at high frequency leading to an effect called current collapse. This is proposed to be related to trapping states at the gate dielectric/semiconductor interface and in turn this may be improved by using Atomic Layer Deposition (ALD) to deposit the dielectric. Oxford Instruments Plasma Technology provide innovative solutions for ALD, Atomic Layer Etching (ALE) and PECVD working closely with our customers to help them solve their problems. With the passion and creativity seen at this year’s ISPSD and look forward to seeing what the next 30 years will bring!

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Author: Dr Mark Dineen