1 kV Self-Aligned Vertical GaN Superjunction Diode

This work demonstrates vertical GaN superjunction (SJ) diodes fabricated via a novel self-aligned process. The SJ comprises n-GaN pillars wrapped by the charge-balanced p-type nickel oxide (NiO). After the NiO sputtering around GaN pillars, the self-aligned process exposes the top pillar surfaces without the need for additional lithography or a patterned NiO etching which is usually difficult. The GaN SJ diode shows a breakdown voltage (B V) of 1100 V, a specific on-resistance (
${R}_{\text {ON}}{)}$
of 0.4
$\text{m}\Omega \cdot $
cm2, and a SJ drift-region resistance (
${R}_{\text {dr}}{)}$
of 0.13
$\text{m}\Omega \cdot $
cm2. The device also exhibits good thermal stability with B V retained over 1 kV and
${R}_{\text {ON}}$
dropped to 0.3
$\text{m}\Omega \cdot $
cm2 at
$125 ^{\text {o}}\text{C}$
. The trade-off between B V and
${R}_{\text {dr}}$
is superior to the 1D GaN limit. These results show the promise of vertical GaN SJ power devices. The self-aligned process is applicable for fabricating the heterogeneous SJ based on various wide- and ultra-wide bandgap semiconductors.