Light-emitting diodes with surface gallium nitride p–n homojunction structure formed by selective area regrowth

Abstract

In this study, the blue light-emitting diode (LED) structures based on gallium nitride (GaN) were presented. Each structure possessed a surface GaN p–n junction, which was formed through selective area regrowth on an InGaN/GaN multiple quantum well (MQW) structure and served as the carrier injector. The LEDs that showed efficient hole injection and current spreading were configured to form a p -type GaN layer between the MQW and regrown n -type GaN top layer. These LEDs exhibited higher luminous efficiency and lower operation voltage than the LEDs with regrown p -type GaN top layers. The LEDs with n -type GaN top layers emitted single-peak spectra at approximately 450 nm under a forward bias. The UV peak at 365 nm (i.e., the GaN band-edge emission) was absent because the regrown surface GaN p–n junctions behaved as carrier injectors rather than photon injectors. In other words, the single-peak blue emission was not generated by the optical pumping of UV light emitted from the surface p–n GaN homojunction.

Current Spreading in Back-Contacted GaInP/GaAs Light-Emitting Diodes

“…The DDCT injection utilizes bipolar electron and hole diffusion currents to inject charge carriers into ARs located outside the p-n junction. This is possible via lateral heterojunctions (LHJs) [15]- [18] located above a uniform AR as illustrated in Figs. 1(b) and 1(c) for the GaInP/GaAs DDCT-LED studied in this work.…”

Developments for enhancing the luminous intensity of LEDs by optimizing their structures

“…Therefore, to balance the reflectance and the Ohmic contact behavior, there is another layer called indium tin oxide (ITO), which is a transparent conducting material that can be deposited between p-GaN and the metals. The transparency of ITO will enable the passing through of the photons, while its electrical property can make a good Ohmic contact with p-GaN [28]. In addition, it is also served as a current spread layer to avoid the crowd of current that might cause the overheating problem [29].…”

Assessment of the optical and electrical properties of light-emitting diodes containing carbon-based nanostructures and plasmonic nanoparticles: a review

“…The emissive layer is also known as the active luminescent region of an LED, where electron-hole recombination occurs. Light-emitting diodes and OLED are capable of emitting in the entire visible spectrum: GaAsP (red), GaN (green, blue/green), PPV (yellow/green), MEH-PPV and BCHA-PPV (yellow/ orange), PPE-PPV (blue), and MDMO-PPV (red) [77][78][79][80][81][82][83][84]. Among these polymers, PPV appears to be the most popular light-emitting polymer.…”