New Approaches to Realizing High Power Nitride Based Field Effect Transistors

High breakdown voltage, excellent current carrying capabilities, high electron saturation velocity, high mobility, good thermal properties, chemical inertness, and radiation hardness of nitride semiconductors make them uniquely suited for high power applications. However, new approaches are needed to achieve their full potential. We report on several key innovations that include (1) the use of Perforated Channel (PC) design (to control and minimize the parasitic and on resistances and off and on transistor capacitances for faster switching and sharply reduced losses); (2) surface application of Low Conducting Layers (LCLs) (to control the properties and stability of ungated surfaces and dramatically increase the breakdown voltage); (3) the combination of these two approaches (for achieving the ultimate power performance at the highest switching frequencies with minimum losses); (4) novel device geometries (combining the best features of lateral and vertical devices for normally-off transistors with unprecedented power handling capability); (5) improved control of self-heating and better heat dissipation using the PC channel design. We also review our recent results exploring the PC channel and LCL designs [1-3]. These experimental and simulation results demonstrated a sharp increase in the breakdown voltage, a large enhancement of the cutoff frequency, a better device stability and smaller spreading of the device parameters for higher yield, improved manufacturability, and smaller self-heating due to a lower thermal impedance.

[[1]] G. Simin, M. Islam, M. Gaevski, J. Deng, R. Gaska, and M. Shur, “Low RC-constant Perforated-Channel HFET”, IEEE Electron Device Letters, 35  (2014)

[2] M. Gaevski, Jianyu Deng, A. Dobrinsky, R. Gaska, M. Shur, and G. Simin, Static and transient characteristics of GaN power HFETs with low-conducting coating, physica status solidi, Article first published online: 24 MAR 2014 | DOI: 10.1002/pssc.201300541

[3] G Simin, M Shur, R Gaska, Semiconductor device with low-conducting buried and/or surface layers - US Patent Application 20,130,126,905 (2013)