Metal‐Insulator‐Semiconductor Structure‐Based InGaN/GaN Micro‐Light‐Emitting Devices with Superior External Quantum Efficiency

In this article, InGaN/GaN micro‐light‐emitting diodes (micro‐LEDs) with innovative device structures are fabricated to suppress surface nonradiative recombination and improve device efficiency. A metal‐insulator‐semiconductor (MIS) sidewall structure enables the application of sidewall bias to adjust the surface recombination of micro‐LEDs. MIS micro‐LEDs with various mesa dimensions are fabricated and characterized. Current density‐voltage ( J‐V) measurements show the increase in surface defects‐assisted tunneling current is attributed to a positive sidewall bias lowering the energy difference between the surface defect states and electron energy states, thereby decreasing the surface recombination and enhancing the external quantum efficiency (EQE) of the device. The increase or decrease in measured device EQE is approximately proportional to the magnitude of the positive or negative sidewall bias, which is well‐explained by the analytical model. The EQE of the MIS micro‐LED with a mesa dimension of 8 µm can be enhanced from 20.0% to 30.7% at a low injection current density (0.625 A cm −2 ) by applying a +20 V sidewall bias, which is comparable to the performance of state‐of‐the‐art organic‐LEDs (OLEDs). More importantly, the maximum EQE of the 8 µm MIS micro‐LED is measured to be ≈53.9% at 23.3 A cm −2 , which is the highest reported EQE to the best of the knowledge.