Improvement of carrier injection symmetry and quantum efficiency in ıngan light-emitting diodes with mg delta-doped barriers
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The effect of delta-doping of In0.06Ga0.94N barriers with Mg on the quantum efficiency of blue light-emitting-diodes (LEDs) with active regions composed of 6 (hex) 3-nm In0.15Ga0.85N is investigated. Compared to the reference sample, delta-doping of the first barrier on the n-side of the LED structure improves the peak external quantum efficiency (EQE) by 20%, owing to the increased hole concentration in the wells adjacent to the n-side, as confirmed by numerical simulations of carrier distributions across the active region. Doping the second barrier, in addition to the first one, did not further enhance the EQE, which likely indicates compensation of improved hole injection by degradation of the active region quality due to Mg doping. Both LEDs with Mg delta-doped barriers effectively suppress the drop of efficiency at high injection when compared to the reference sample, and the onset of EQE peak roll-off shifts from similar to 80 A/cm(2) in the reference LED to similar to 120 A/cm(2) in the LEDs with Mg delta-doped barriers.