An InGaN amber nano-light-emitting diode with external quantum efficiency of 10.1%

Efficient long-wavelength nano-light-emitting diodes (nano-LEDs) are essential for ultrahigh-density monolithic RGB micro-displays, yet their efficiency usually deteriorates as device size shrinks because sidewall-related nonradiative recombination becomes increasingly important. Here, we demonstrate electrically injected planar InGaN amber nano-LEDs with a circular mesa diameter of ∼840 nm fabricated by a conventional top-down process with conformal ALD-Al2O3 sidewall passivation. The device emits at 608 nm and exhibits an ultralow reverse leakage current of ∼10−14 A at −5 V. A peak external quantum efficiency of 10.1% is achieved at ∼12 A/cm2, exceeding that of a 20 μm device from the same wafer (∼9.8% at ∼4 A/cm2). Analysis using an ABC model indicates that downscaling increases the sidewall-related SRH term, but this penalty is overcompensated by enhanced light extraction efficiency in the nanoscale mesa. The fluorescence lifetime imaging microscopy mapping further reveals spatially resolved carrier dynamics that are closely correlated with strong carrier localization in the high-In-content red-emitting quantum wells, which helps suppress sidewall nonradiative recombination. These results establish top-down long-wavelength III-nitride nano-LEDs as a viable route toward ultrahigh-resolution monolithic micro-displays.