Heavily Si-doped pulsed sputtering deposited GaN for tunneling junction contacts in UV-A light emitting diodes

We report the characteristics of heavily Si-doped GaN prepared by pulsed sputtering deposition (PSD) and its application as tunneling junction (TJ) contacts for nitride-based light-emitting diodes (LEDs). We determined that the use of PSD allows us to grow extremely heavily Si-doped wurtzite GaN epitaxial layers with [Si] = 1.0 × 1021 cm−3 on commercially available UV-A LED wafers. Then, we processed these samples into LED structures to investigate their device characteristics as TJ-contact LEDs. Compared to commercially available UV-A LEDs with transparent conductive oxide contacts, TJ-contact LEDs with [Si] = 1.0 × 1021 cm−3 at the tunnel-junction interface showed lower differential resistance and, consequently, worked well under a high injection current density of ∼1 kA/cm2 without any degradation. These results indicate that PSD-grown heavily doped n-type GaN is promising for application as a TJ-contact in group III nitride-based optoelectronic devices.