Conference Paper

Effect of passivation on AlGaN/GaN HEMT device performance

Sch. of Electr. Eng., Cornell Univ., Ithaca, NY
DOI: 10.1109/ISCS.2000.947182 Conference: Compound Semiconductors, 2000 IEEE International Symposium on
Source: IEEE Xplore

ABSTRACT AlGaN/GaN HEMTs are suitable for high power applications because
of their high breakdown voltages and high currents. However, the large
signal performance of these devices is not as good as one would expect
from the DC performance of the device. The large signal performance of
the device is improved by depositing a thin layer of SiN by PECVD. In
this work silicon nitride (SiN) was deposited in a variety of conditions
on AlGaN/GaN HEMT structures on sapphire substrates to study the impact
of the quality of SiN on the DC, breakdown, small signal and large
signal performance of the device. A maximum increase in the output power
from 1.3 W/mm to 2.3 W/mm at 4 GHz, 20 V bias was observed with a SiN
passivation film, grown in NH3 rich conditions and which gave
the least etch rate of 25 nm/min in buffered oxide etch (6:1). This
increase in power is mainly due to the increase in DC current. This is
clearly shown by plotting the RF dynamic loadline for an unpassivated
and passivated device