Experimental investigation of spontaneous emission
characteristics of InGaAs-based indium-rich
cluster-induced special quantum structure
Ming Zheng (郑 明)
1
, Qingnan Yu (于庆南)
1
, Hanxu Tai (邰含旭)
1
,
Jianwei Zhang (张建伟)
2
, Yongqiang Ning (宁永强)
2
, and Jian Wu (吴 坚)
1,
*
1
Department of Applied Physics, Beihang University, Beijing 100191, China
2
State Key Laboratory of Luminescence and Application, Changchun Institute of Optics, Fine Mechanics and Physics,
Chinese Academy of Sciences, Changchun 130033, China
*Corresponding author: jwu2@buaa.edu.cn
Received November 5, 2019; accepted January 3, 2020; posted online April 26, 2020
The unamplified spontaneous emission (SE) is one of the important physical processes of the light–matter
interaction in a diode laser in terms of Einstein’s theory. The recent research on a kind of new indium-rich cluster
(IRC) laser structure did not reveal SE characteristics of the IRC structure, as its unusual quantum confined
structure made it difficult to acquire correctly the SE spectra through theoretical simulation or previous exper-
imental techniques. Thus, in this Letter, we firstly established a convenient and effective experimental approach
to acquire SE spectra of the IRC structure by the measurement of amplified SEs from dual facets of a single edge-
emitting chip with little sample processing. With the proposed method, the special SE spectra due to the IRC
effect were observed. Then, the SE formation mechanism and characteristics in the IRC structure were analyzed
by comparing the experimental data with theoretical SE spectra using a standard InGaAs/GaAs quantum well
with similar material composition. This research provides a useful tool to investigate the SE characteristics of
any non-standard diode laser structure and is very meaningful to develop a new type of IRC lasers.
Keywords: semiconductor laser; spontaneous emission; indium-rich cluster; InGaAs/GaAs; strain.
doi: 10.3788/COL202018.051403.
The unamplified spontaneous emission (SE) intensity is
an important parameter to consider in the design and in-
vestigation of semiconductor lasers, as it describes a fun-
damental physical process in light–matter interaction in
terms of Einstein’s theory
[1–6]
. In general, the SE of a classic
or standard diode laser structure can be characterized by
theoretical simulation
[7]
. However, the theoretical calcula-
tion cannot fully reveal the SE characteristics of a non-
standard quantum confined structure due to the existence
of any defects in a true material system. Therefore, some
experimental methods were developed in the past. These
approaches involved the direct SE measurement by
opening a top-contact window from the sample
[8]
, the mea-
surement of amplified SE (ASE) spectra by fabricating a
special multi-section edge-emitting sample
[9]
, or the
measurement of the rays traveling nearly parallel to the
top surface by utilizing a buried hetero-structure
[10]
.A
common point of these methods is that additional and
strict sample processing is required. This limits their ap-
plication in many cases, as it is difficult to prepare s uch a
sample. Therefore, a simpler and effective experimental
approach to obtaining the SE spectra of any diode laser
structure is expected firstly.
The recent research on a kind of new indium-rich cluster
(IRC) laser structure has shown that the IRC effect would
give rise to an irregular quantum confined structure in the
InGaAs-based material system
[11,12]
, where the IRCs were
commonly regarded as a kind of defect to avoid for a stan-
dard InGaAs quantum well in the past. This means that it
is difficult to characterize correctly the SE characteristics
of the IRC structure through purely theoretical simula-
tion, and it is necessary to develop a simpler and effective
experimental approach to solve the SE characterization
problem for the IRC quantum confined laser structure.
Based on the above statement, here, we firstly fabri-
cated the IRC laser samples and developed a simpler
and effective experimental approach to acquire the SE
spectra for the InGaAs-based IRC laser structure. The
method used only a single edge-emitting chip without
any complicated sample processing except coating by
complete transmittance at one facet of the chip. This
avoided unnecessary measurement errors from inaccurate
sample processing. Subsequently, the experimental SE
data of the IRC structure were analyzed by comparing
the theoretical SE spectra using a standard InGaAs/GaAs
quantum well with similar material composition. Finally,
the conclusions were stated.
The IRC laser sample was designed with In
0.17
Ga
0.83
As
as the original active layer material, the thickness of which
was 10 nm. A 2-nm-thick GaAs strain-compensating layer
was embedded between the In
0.17
Ga
0.83
As active layer and
a GaAs
0.92
P
0.08
barrier to relieve the high compressive
strain between the active layer and the barrier. The wave-
guide was the AlGaAs material with a thickness of 2 μm.
The whole structure is grown on the GaAs (001) substrate
with metal organ ic chemical vapor deposition. The tem-
perature for the material deposition was 660°C. The
higher temperature of 660°C was applied here to increase
COL 18(5), 051403(2020) CHINESE OPTICS LETTERS May 2020
1671-7694/2020/051403(5) 051403-1 © 2020 Chinese Optics Letters
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