Investigation of Electrical and Optical Properties of AlGaInP Red Vertical Micro-Light-Emitting Diodes With Cu/Invar/Cu Metal Substrates
Shreekant Sinha, Fu‐Gow Tarntair, Cheng-Han Ho, Yuh‐Renn Wu, Ray‐Hua Horng
Abstract
This research studies the performance of n-side up thin-film AlGaInP-based vertical micro-light-emitting diodes (V- μLEDs) with four different chip sizes, 100×100, 70×70, 50×50, and 25×25 μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , on a 50 μm thick composite metal (copper/Invar/copper; CIC) substrate. The LEDs were fabricated to understand the electrical and optical properties of AlGaInP V- μLEDs as functions of chip sizes. For device performance, the small LEDs provide a larger current density under the same voltage and present smaller forward voltage, a low red-shift phenomenon, and low output power density. For the external quantum efficiency (EQE) of device, larger LEDs exhibit maximum EQE at lower current density as compared to smaller LEDs. The injection of a small current at the same current density obtains the emission image. The obtained data suggest that the smallest V- μLEDs exude a sidewall effect that could impact the device performance.