Enhanced Light Extraction of Infrared AlGaAs-Based LEDs With Micron Array

Abstract

In order to improve the light extraction efficiency (LEE) of a plane AlGaAs-based LED (Device A), three different surface periodic micron-scale arrays, micron pillar (Device B), micron truncated cone (Device C) and micron cone (Device D), are prepared by the conventional ultra-violet (UV) lithography. The morphology of the three devices B–D is characterized by a scanning electron microscopy (SEM). The periodic array structures improve the photon escape probabilities. In comparison to the Device A, the light output powers (LOPs) of the Devices B–D increase 54.0%, 145.5% and 157.2% at an injection current of 500 mA, respectively. Moreover, we use the Monte Carlo ray-tracing method to simulate the LEE of the four devices. The energy distribution of the Devices B-D is more concentrated in the middle region in contrast with the Device A.

Keywords

• Light emitting diodes
• micron array
• light extraction efficiency
• ultra-violet lithography
• total reflection