A Study on the Hydrogen Effect and Reliability of a Depletion-Mode AlGaN/GaN MISFET Device

Through electrical characteristic testing of the
$\text{AlGaN}/\text{GaN}$
metal insulator semiconductor field effect transistor (MISFET) before and after hydrogen exposure, the results show that: (1) After 500 hours of hydrogen treatment, the threshold voltage of the device shifts from
$- 16.98{\mathrm{\ V}}$
to
$11.53{\mathrm{\ V}}$
, with a threshold change of
$5.45{\mathrm{\ V}}$
. It is speculated that the device introduced some defects during the experiment, and these defects can adsorb electrons during testing, resulting in a large positive drift range of the threshold voltage. (2) The transconductance curve before and after the experiment shows that hydrogen treatment increases the peak transconductance of the device, with Gmmax increasing from
$281\text{mS}/\text{mm}$
to
$340\text{mS}/\text{mm}$
, an increase of approximately
$21{\mathrm{\% }}$
. Transconductance represents the gate control ability over the channel. (3) The output characteristics at drain-source voltage
${\mathrm{V}}_{\text{DS}}$
from 0 to
$1{\mathrm{\ V}}$
and gate-source voltage
${\mathrm{V}}_{\text{GS}}$
of
$0{\mathrm{\ V}}$
show that under the same bias voltage, hydrogen treatment significantly reduces the leakage current of the device. IDS decreases from
$9.45{\mathrm{\ A}}$
in the fresh device to
$7.08{\mathrm{\ A}}$
, a decrease of
$25{\mathrm{\% }}$
. (4) The
$1/\mathrm{f}$
noise performance is improved, and the device after hydrogen treatment has a lower noise level. Through low-frequency noise (LFN) analysis, the trap density in the
$\text{AlGaN}/\text{GaN}$
MISFET device decreases by approximately one order of magnitude after hydrogen treatment, which leads to a reduction in depletion electrons in the device channel Two-Dimensional Electron Gas (2DEG). The mechanism for the reduction in trap density can be attributed to hydrogen passivation defects at the
$\text{AlGaN}$
surface,
$\text{AlGaN}$
barrier layer, and heterojunction interface. The research results of this article have certain reference value for the design and application of
$\text{AlGaN}/\text{GaN}$
MISFET devices.