High-Performance 348 nm AlGaN/GaN-Based Ultraviolet-Light-Emitting Diode with a SiN Buffer Layer

Abstract

A 348 nm ultraviolet-light-emitting diode (UV-LED) based on an AlGaN/GaN single quantum well (SQW) with a high optical power is reported. In this structure, a thin SiN buffer is introduced before the growth of a conventional low-temperature GaN buffer layer. Such a buffer layer can dramatically reduce the density of threading dislocation as we have previously reported. Since the optical performance of UV-LED is generally known to be sensitive to the density of threading dislocations, unlike the InGaN/GaN-based blue LED, our UV-LED has a higher optical power than that of a similar structure but without a SiN buffer layer. Since our new buffer technology is much easier than the so-called epitaxial lateral overgrowth (ELO) or pendeoepitaxy method, it is highly recommended for use in the fabrication of GaN-based optical devices, particularly AlGaN/GaNbased UV-LED.

Investigation of optical‐output‐power degradation in 365‐nm UV‐LEDs

“…It was found that the lifetime of 365 nm UV LEDs depends strongly on dislocation density. The activation energy of UV LEDs with dislocation density of 1x10 8 …”

“…The ELO process, however, is a highly complex process. Therefore, it is desired to grow GaN films with dislocation density of less than 1x10 8 …”

Reduction of dislocation density in heteroepitaxial GaN: role of SiH4 treatment

“…It has been found recently that threading dislocations reduce the light output of UV LEDs much more than they do for blue GaN LED's [1][2][3][4]. Also for laser diodes a low density of dislocations is essential for extensions of their lifetime.…”

Near ultraviolet InGaN/GaN MQWs grown on maskless periodically grooved sapphire substrates fabricated by wet chemical etching

“…Especially for the ultraviolet light-emitting devices, it is very difficult to grow high performance ultraviolet MQWs on sapphire substrate. The point is totally different from InGaN-based blue/green LEDs because the performance of InGaN/GaN-based blue/green LED is not so sensitive to dislocations [3,4]. The insensitiveness of blue/green LED to the existed dislocation has been generally accepted to be due to the localization of excitons at certain potential minima, such as InGaN quantum dots [5] or quantum disks [6], formed by fluctuation of indium composition in InGaN QWs [7].…”