Impact of Channel Thickness on the Large-Signal Performance in InAlGaN/AlN/GaN HEMTs with an AlGaN Back Barrier
Journal article, 2019

The impact of varying the GaN channel layer thickness (t ch ) in InAlGaN/AlN/GaN HEMTs with C-doped AlGaN back barriers is investigated. t ch was 50, 100, and 150 nm, and the gate length of the fabricated HEMTs ranged from 50 to 200 nm. It is found that short-channel effects (SCEs) are significantly mitigated with a small t ch . For HEMTs with a gate length of 50 nm, the drain-induced barrier lowering changes from 40 to 93 mV/V as t ch is increased from 50 to 150 nm. On the other hand, it is shown that dispersive effects are more severe for a smaller t ch , as demonstrated by a sixfold increase in the dynamic ON-resistance for t ch = 50 nm compared to t ch = 150 nm. The tradeoff between dispersion and SCEs is reflected in large-signal measurements at 30 GHz. The 50-nm channel, mainly limited by dispersion, exhibits an output power of 3.5 W/mm. The thicker channels reach a maximum of around 5 W/mm, but for different gate lengths due to the difference in severity of the SCEs. This paper elucidates the interplay between SCEs and dispersion related to t ch , its consequences for the large-signal performance and for the limitation in downscaling of the gate length.

dispersion

Back barrier (BB)

channel thickness

large signal

short-channel effects (SCEs)

GaN HEMT

double heterojunction (DH) HEMT

InAlGaN

Author

Anna Malmros

Chalmers, Microtechnology and Nanoscience (MC2), Microwave Electronics, Microwave Electronics

P. Gamarra

Thales Group

Mattias Thorsell

Chalmers, Microtechnology and Nanoscience (MC2), Microwave Electronics, Microwave Electronics

Hans Hjelmgren

Chalmers, Microtechnology and Nanoscience (MC2), Microwave Electronics, Microwave Electronics

C. Lacam

Thales Group

Sylvain Laurent Delage

Thales Group

Herbert Zirath

Chalmers, Microtechnology and Nanoscience (MC2), Microwave Electronics

Niklas Rorsman

Chalmers, Microtechnology and Nanoscience (MC2), Microwave Electronics, Microwave Electronics

IEEE Transactions on Electron Devices

0018-9383 (ISSN)

Vol. 66 1 364-371 8563102

Subject Categories

Telecommunications

Signal Processing

Other Electrical Engineering, Electronic Engineering, Information Engineering

DOI

10.1109/TED.2018.2881319

More information

Latest update

3/25/2020