Characteristics of deep ultraviolet AlGaN-based light emitting diodes
with p-hBN layer
K.X. Dong
a,b
, D.J. Chen
a,
n
, J.P. Shi
c
, B. Liu
a
,H.Lu
a
, R. Zhang
a
, Y.D. Zheng
a
a
Key Laboratory of Advanced Photonic and Electronic Materials, Collaborative Innovation Center of Advanced Microstructures, School of Electronic Science
and Engineering, Nanjing University, Nanjing 210093, China
b
The School of Electronic and Electrical Engineering, Chuzhou University, Chuzhou 239000, China
c
College of Physics and Electronic Information, Auhui Normal University, Wuhu 241000, China
HIGHLIGHTS
AlGaN DUV LED structure with
p-type hBN layer is designed.
The carrier injection, radiative
efficiency, and EL intensity are
significantly improved.
The designed LED can increase
the light extraction efficiency
more than 250%.
GRAPHICAL ABSTRACT
Advantges of AlGaN deep ultraviolet light emiting didoes with p-hBN layer. Schematic structer of pro-
posed LED. EL intensity and output power, and output angular power intensity for conventional LED and
designed LED. Kexiu Dong, Dunjun Chen, Jianping Shi, Bin Liu, Hai Lu, Rong Zhang, Youdou Zheng.
article info
Article history:
Received 31 July 2015
Accepted 27 August 2015
Available online 28 August 2015
Keywords:
AlGaN
UV LED
p-hBN
abstract
The AlGaN-based deep ultraviolet (DUV) light-emitting diodes (LEDs) with p-hBN layer are investigated
numerically. In comparison with the conventional AlGaN DUV LEDs, the proposed LED can significantly
improve the carrier injection, radiative efficiency, as well as the electroluminescence (EL) intensity under
the same applied forward bias. Simultaneously, the light extraction efficiency in the LED using p-hBN
instead of p-AlGaN exhibits a more than 250% increase at the applied voltage of 7.5 V due to the smaller
loss of reflection and absorption of the emitted light.
& 2015 Elsevier B.V. All rights reserved.
1. Introduction
Solid-state AlGaN-based deep ultraviolet (DUV) light emitting
diodes (LEDs) have attracted increasing interest due to their ex-
cellent advantages such as miniaturization, mercury-free, low
power consumption, and a long operational lifetime [1–3], which
are widely used in many fields including surface disinfection, air
and water purification, medical phototherapy, currency validation,
analytical instrumentation, and biological agent detection [4,5] .
With the gradual improvements of the crystal quality of the high-
Al-content AlGaN materials, the last decade witnessed the fast
development of AlGaN-based quantum well (QW) DUV LEDs. The
external quantum efficiency (EQE) around 10% for LED with the
emission wavelength between 270 and 280 nm and over 3% for
LED with the emission wavelength ranging from 255 to 280 nm
have been reported [1,6]. However, the high-Al-content DUV LEDs
show very low EQE compared with InGaN visible LEDs in which
EQE is over 70%. This low EQE may be attributed to the low carrier
injection and radiative recombination efficiency in QW, as well as
the poor light extraction efficiency.
Generally, in order to enhance the electron injection efficiency
and electron–hole radiative recombination efficiency in QW for
AlGaN-based DUV LEDs, the Al-rich p-AlGaN layer has been em-
ployed as an electron blocking layer. Unfortunately, in addition to
block the electron overflow through QW toward the p-AlGaN
layer, such layers also reduce the hole injection from low-Al-
content p-AlGaN contact layer into QW due to the unavoidable
valence-band offset, which limits the electron–hole recombination
Contents lists available at ScienceDirect
journal homepage: www.elsevier.com/locate/physe
Physica E
http://dx.doi.org/10.1016/j.physe.2015.08.035
1386-9477/& 2015 Elsevier B.V. All rights reserved.
n
Corresponding author. Fax: þ 86 25 83685476.
E-mail address: djchen@nju.edu.cn (D.J. Chen).
Physica E 75 (2016) 52–55