GaN/InAlN/AlN/GaN high-electron mobility transistors with Schottky-barrier gate and selectively etched access regions

Fabrication of unique InAlN barrier-based transistors with normally-off channel stem from the 7FP project MORGAN. Developed devices point on technologically simple method of designing Schottky-contact-based normally-off transistors with a high breakdown voltage and low leakage currents.  Demonstrated transistors open a way towards robust high-power switches, as well as towards new generation of fast logic circuits.  New technology is represented by a method of plasma etching of transistor access regions, which is highly selective and harmless to transistor performance. The concept was proposed and device processing was performed at the Institute of Electrical Engineering Slovak Academy of Sciences.

(a) Calculated energy band and electron concentration profiles at (GaN)/InAlN/AlN/GaN HEMT access regions before and after etching the GaN cap in equilibrium. (b) Sketch of the completed HEMT. (c) AFM image of etch test structure showing a 2.5 µm-wide etched window in the GaN cap.

Jurkovič, M., Gregušová, D., Palankovski, V., Haščík, Š., Blaho, M., Čičo, K., Fröhlich, K., Carlin, J., Grandjean, N., and Kuzmík, J.: Schottky-barrier normally off GaN/InAlN/AlN/GaN HEMT with selectively etched access region, IEEE Electron Dev. Lett. 34 (2013) 432-434.

Jurkovič, M., Gregušová, D., Haščík, Š., Blaho, M., Molnár, M., Palankovski, V., Donoval, D., Carlin, J.-F., Grandjean, N., and Kuzmík, J.: GaN/InAlN/AlN/GaN normally-off HEMT with etched access region. In: WOCSDICE-EXMATEC 2012. Proc. 36th European Workshop on Compound Semicond. Devices and Integrated Circuits and 11th Expert Evaluation & Control of Compound Semicond. Mater. and Technol. Eds. Y. Cordier and J.-Y. Duboz. Island of Porquerolles: CRHEA & CNRS 2012.