For you Star Wars fans, we remember Admiral Ackbar, with his vast experience as a warrior, commenting on a situation during a battle. See this YouTube video
Recently I met with Alex Lidow, CEO of Efficient Power Conversion (EPC), and co-inventor of the HEXFET power MOSFET in 1978, a power transistor that launched the modern power conversion market and displaced the aging bipolar transistor. He told me that the HEXFET was actually born from a mistake when what was supposed to be 12.5 micron lines were made to be 10 micron in a design he was drawing by hand. That mistake netted International Rectifier over $930M in royalties.
EPC CEO Alex Lidow with Editor Steve T. in Scottsdale, AZ. The Second Edition of GaN Transistors for Efficient Power Conversion is a great educational resource for designers who want to understand the workings of the GaN power element.
Dr. Lidow is also in the midst of a battle of sorts, that of bringing the GaN transistor process to its full capability via an in-depth understanding and use of quantum mechanics and eliminating semiconductor ‘traps’ where they matter such as in improving RON . GaN technology is still far away from its theoretical performance limits and Dr. Lidow suggested that eliminating ‘traps’, in areas where they mostly affect performance, will be a significant first phase of this endeavor. Like Admiral Ackbar, Dr. Lidow recognizes a ‘trap’ and how it can be rendered ineffective to improve the GaN process.
We discussed the quest to improve the GaN process far beyond the incredibly performing success of what it is today as a power element. GaN’s rise as a power element is due to its large band gap ( ∼ 3.4 eV) and high electron saturation velocity as well HEMT structures available in the Alx Ga1−x N/GaN system. Dr. Lidow has chosen his company’s devices to be an Enhancement-Mode Structure. The eGaN FET transistors are very similar to lateral Silicon FETs.
Effectively, the reliability of GaN High-Electron-Mobility-Transistors (HEMT) are limited by ‘trapping’ phenomena that may be due to trapping states at the interface of dissimilar crystal structures, or Carbon doping2 . Dr. Lidow commented that electrons will fall into these ‘traps’ which act like tiny Moon craters, and are ‘trapped’ which will increase the device’s impedance.
In recent experiments1 it has been demonstrated that the transistor’s ON resistance recovery was thermally activated after the OFF-state high bias condition in a C-doped GaN buffer device. This may have been due to the emission of electrons captured in Carbon-related buffer traps during the OFF-state high bias conditions.
I expect more to come regarding this effort which should yield improvements in efficiency in the GaN power element. Keep watching on Planet Analog and EDN Power for more progress on this front by Dr. Lidow and his team.
‘May the (Electromotive) Force be with you”
1 G. Meneghesso, M. Meneghini, R. Silvestri, P. Vanmeerbeek, P. Moens, and E. Zanoni, “High voltage trapping effects in GaN-based metal–insulator–semiconductor transistors,” Jpn. J. Appl. Phys., vol. 55, no. 1S, pp. 01AD04-1–01AD04-5, Jan. 2016.
2 Alessandro Chini, Gaudenzio Meneghesso, Fellow, IEEE, Matteo Meneghini, Senior Member, IEEE, Fausto Fantini, Senior Member, IEEE, Giovanni Verzellesi, Senior Member, IEEE, Alfonso Patti, and Ferdinando Iucolano, “Experimental and Numerical Analysis of Hole Emission Process From Carbon-Related Traps in GaN Buffer Layers”, IEEE TRANSACTIONS ON ELECTRON DEVICES, VOL. 63, NO. 9, SEPTEMBER 2016