Effect of doping in p-GaN gate on DC performances of AlGaN/GaN normally-off scaled HFETs

This work presents the effect of p-type GaN gate doping concentration on the DC performances of 60nm gate length of AlGaN/GaN Normally-off HFET using 2D Atlas TCAD simulation. An extensive simulation is carried out for the proposed device to explore the parameters such as drain current, transconductance, energy band diagram and surface potential with respect to p-type GaN gate doping concentration (P
_n
). The concentration is varied from 5×10
¹⁷
to 1×10
¹⁹
and it is verified that with increase in P
_n
the drain current increases and transconductance decreases. An important conclusion has been figured out that when the P
_n
falls below 1×10
¹⁸
, the HFET device lost its normally-off mode which is not desirable for the high power switching application. Hence proper optimization of P
_n
is indispensable to preserve the normally-off mode operation and at the same time enhancing certain performance parameters.