Stable electrical performance of AlGaInP-based red micro-light emitting diode by controlling interfacial morphologies of metal contacts

Abstract

The stable electrical performance of micro-light-emitting diodes (micro-LEDs) is critical to display application. We investigated the effect of the interface morphologies of contacts to n-AlInP on the electrical stability of AlGaInP-based red micro-LEDs. Regardless of chip sizes (100 pm or 10 pm-size), micro-LEDs with Pd/Ge contacts gave lower and stable forward voltages than those with AuGe/Ni/Au contacts. When annealed at 450 ?C, the AuGe/Ni/Au contact underwent seriously inhomogeneous interfacial reactions, resulting in a large variation of interfacial morphologies across the whole contact/AlInP interface. However, the Pd/Ge contact exhibited similar morphologies across the whole interface when annealed. Further, when operated at 800 A/cm2, micro-LEDs with the Pd/Ge contacts underwent less electrical degradation than the ones with the AuGe/Ni/Au contacts. Based on the electrical and scanning transmission electron microscope (STEM) results, the unstable electrical behavior of red micro-LEDs with the AuGe/Ni/Au contact is discussed. ? 2021 Elsevier B.V. All rights reserved.