Low-Resistance Ni/Ag Contacts on GaN-Based p-Channel Heterojunction Field-Effect Transistor

In this work, we have demonstrated the Ni/Ag contacts on p-channel heterostructure field-effect transistors (p-HFETs) based on the p-GaN/AlGaN/GaN/Si platform. Using an optimal contact condition, where Ni/Ag (1/120 nm) was deposited and annealed at 550 °C for 180 s in
$\text{O}_{{2}}$
ambient, a low contact resistance (
$27.44 \Omega \cdot $
mm at 50 mA/mm) and a low Schottky barrier height (SBH) (0.479 eV) have been obtained. The p-HFETs with Ni/Ag contacts exhibit a very slight Schottky character, resulting in a satisfactory ON-resistance (
${R} _{ \mathrm{\scriptscriptstyle ON}}$
) of 2.1
$\text{k}\Omega \cdot $
mm. Furthermore, the p-HFETs exhibit excellent electrical properties including a threshold voltage (
${V} _{{\text {th}}}$
) of −1.91 V, an ON-state current (
${I} _{ \mathrm{\scriptscriptstyle ON}}$
) of 2.46 mA/mm, and an
${I} _{ \mathrm{\scriptscriptstyle ON}}/{I} _{ \mathrm{\scriptscriptstyle OFF}}$
ratio of
${\sim } 10^{{6}}$
. These results present a great potential of cost-effective Ni/Ag contacts on p-HFETs.