Low-temperature growth of n ++ -GaN by metalorganic chemical vapor deposition to achieve low-resistivity tunnel junctions on blue light emitting diodes

We report on low-resistivity GaN tunnel junctions (TJ) on blue light-emitting diodes (LEDs). Si-doped n ++ -GaN layers are grown by metalorganic chemical vapor deposition directly on LED epiwafers. Low growth temperature (<800 °C) was used to hinder Mg-passivation by hydrogen in the p ++ -GaN top surface. This allows achieving low-resistivity TJs without the need for post-growth Mg activation. TJs are further improved by inserting a 5 nm thick In 0.15 Ga 0.85 N interlayer (IL) within the GaN TJ thanks to piezoelectric polarization induced band bending. Eventually, the impact of InGaN IL on the internal quantum efficiency of blue LEDs is discussed.