1.2-kV Vertical GaN PIN Rectifier With Ion-Implanted Floating Guard Rings

This work reports on the fabrication and properties of a homojunction gallium nitride (GaN) p-i-n (PIN) rectifier fabricated on a free-standing GaN substrate. Uniform device performance is achieved with breakdown voltage (BV)
$ > {1.2}$
kV and low ON-resistance
$\times $
area (
${R}_{{ \mathrm{\scriptscriptstyle ON}}} {A}$
). The statistics of the BV measurements show 58.5% of devices achieve BV
$ > {1.3}$
kV, and 71.1% of devices achieve BV
$ > {1.2}$
kV, as attributed to high quality and control in both epitaxial growth and device process. At room temperature,
${R}_{{ \mathrm{\scriptscriptstyle ON}}} {A}$
is 0.23
$\text{m}\Omega \cdot $
cm2 at a current density (
${J}$
) of 6.9 kA/cm2. The corresponding Baliga’s figure of merit is
${>}{5.97}$
GW/cm2. Temperature-dependent reverse
${I}$
–
${V}$
measurements were performed and show a positive temperature coefficient of 0.42 V/K, indicating the avalanche capability of reverse breakdown. Further analysis with the Poole-Frenkel model on the temperature-dependent measurement suggested that a trap-assisted tunneling process contributed to the reverse leakage current. Floating guard rings (FGRs) formed by nitrogen implantation serve as an effective edge termination technique in these GaN PIN rectifiers, resulting in uniform performance in both forward and reverse bias.