Deep ultraviolet emitting AlGaN quantum wells with high internal quantum efficiency

2009 ◽  
Vol 94 (18) ◽  
pp. 181907 ◽  
Author(s):  
A. Bhattacharyya ◽  
T. D. Moustakas ◽  
Lin Zhou ◽  
David. J. Smith ◽  
W. Hug
Keyword(s):  
Quantum Wells ◽  
Quantum Efficiency ◽  
Internal Quantum Efficiency ◽  
Deep Ultraviolet

scholarly journals A Review of AlGaN-Based Deep-Ultraviolet Light-Emitting Diodes on Sapphire

2018 ◽  
Vol 8 (8) ◽  
pp. 1264 ◽  
Author(s):  
Yosuke Nagasawa ◽  
Akira Hirano
Keyword(s):  
Quantum Wells ◽  
Quantum Efficiency ◽  
Light Emitting Diodes ◽  
Internal Quantum Efficiency ◽  
Threading Dislocation ◽  
Nonradiative Recombination ◽  
Device Structure ◽  
Light Emitting ◽  
Practical Applications ◽  
Deep Ultraviolet

This paper reviews the progress of AlGaN-based deep-ultraviolet (DUV) light emitting diodes (LEDs), mainly focusing in the work of the authors’ group. The background to the development of the current device structure on sapphire is described and the reason for using a (0001) sapphire with a miscut angle of 1.0° relative to the m-axis is clarified. Our LEDs incorporate uneven quantum wells (QWs) grown on an AlN template with dense macrosteps. Due to the low threading dislocation density of AlGaN and AlN templates of about 5 × 108/cm2, the number of nonradiative recombination centers is decreased. In addition, the uneven QW show high external quantum efficiency (EQE) and wall-plug efficiency, which are considered to be boosted by the increased internal quantum efficiency (IQE) by enhancing carrier localization adjacent to macrosteps. The achieved LED performance is considered to be sufficient for practical applications. The advantage of the uneven QW is discussed in terms of the EQE and IQE. A DUV-LED die with an output of over 100 mW at 280–300 nm is considered feasible by applying techniques including the encapsulation. In addition, the fundamental achievements of various groups are reviewed for the future improvements of AlGaN-based DUV-LEDs. Finally, the applications of DUV-LEDs are described from an industrial viewpoint. The demonstrations of W/cm2-class irradiation modules are shown for UV curing.

scholarly journals Enhancement of quantum efficiency in InGaN quantum wells by using superlattice interlayers and pulsed growth

2016 ◽  
Vol 55 (4) ◽  
Author(s):  
Kazimieras Nomeika ◽  
Mantas Dmukauskas ◽  
Ramūnas Aleksiejūnas ◽  
Patrik Ščajev ◽  
Saulius Miasojedovas ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Quantum Efficiency ◽  
Light Emitting Diode ◽  
Internal Quantum Efficiency ◽  
Recombination Coefficient ◽  
Time Resolved ◽  
Mocvd Growth ◽  
Lower Strain ◽  
Type Contact ◽  
Ingan Quantum Wells

Enhancement of internal quantum efficiency (IQE) in InGaN quantum wells by insertion of a superlattice interlayer and applying the pulsed growth regime is investigated by a set of time-resolved optical techniques. A threefold IQE increase was achieved in the structure with the superlattice. It was ascribed to the net effect of decreased internal electrical field due to lower strain and altered carrier localization conditions. Pulsed MOCVD growth also resulted in twice higher IQE, presumably due to better control of defects in the structure. An LED (light emitting diode) structure with a top p-type contact GaN layer was manufactured by using both growth techniques with the peak IQE equal to that in the underlying quantum well structure. The linear recombination coefficient was found to gradually increase with excitation due to carrier delocalization, and the latter dependence was successfully used to fit the IQE droop.

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