227 nm AlGaN Light-Emitting Diode with 0.15 mW Output Power Realized using a Thin Quantum Well and AlN Buffer with Reduced Threading Dislocation Density

Abstract

AlGaN multi-quantum-well (MQW) deep-ultraviolet (DUV) light-emitting diodes (LEDs) fabricated on sapphire substrates with emission at 227 nm are demonstrated. A remarkable enhancement in the DUV LED output power was achieved by using a thin AlGaN quantum well only 1.3 nm in thickness, with atomically flat hetero-interfaces, together with an AlN buffer layer of reduced threading dislocation density. The AlGaN-MQW DUV LEDs exhibited single emission peaks. The output power was 0.15 mW with injection current of 30 mA and the maximum external quantum efficiency was 0.2%, under room temperature pulsed operation.

Influence of Electric Field and Carrier Localization on Carrier Dynamics in AlGaN Quantum Wells

“…Deep UV emitters use high-Al-content AlGaN heterostructures providing emission at the wavelength down to 200 nm. LEDs operating at 247 nm [1], 231 nm [2] and 227 nm [3] have been demonstrated. The shortest operating wavelength of 210 nm has been achieved in AlN-based LED [4].…”

222 nm single‐peaked deep‐UV LED with thin AlGaN quantum well layers

“…It is believed to be particularly important to obtain atomically smooth hetero-interfaces to obtain a high IQE from such a thin QW. The atomically flat hetero-interfaces between 1.3 nm-thick well and 7 nm-thick barrier of the QW emitting region were confirmed by the cross-sectional TEM image [15].…”

“…Since 2007, we developed 227-261 nm AlGaN QW LEDs using high quality AlN buffer on sapphire [14,15]. We obtained cw 1.65 mW output power from 261 nm AlGaN MQW LED.…”

Interface phonon modes in the [AlN/GaN]20 and [Al0.35Ga0.65N/Al0.55Ga0.45N]20 2D multi-quantum well structures

“…The use of AlN buffer layer significantly reduces the dislocation density and improves the overall structural quality of the SL layers as well as the quantum efficiency of the MQW optoelectronic device. 8,29,30,36,37 In order to confirm it, a bi-layer thin film of Al 0.50 Ga 0.50 N(~300 nm)/AlN(~200 nm) (schematic Fig. 2(a)) was also studied for its symmetry allowed Raman phonon modes of AlN-E 2 H and AlN-A 1 (LO) along with the presence of IF modes (Fig.…”