ISSN 1062-8738, Bulletin of the Russian Academy of Sciences: Physics, 2010, Vol. 74, No. 1, pp. 69–71. © Allerton Press, Inc., 2010.
Original Russian Text © L.E. Vorob’ev, V.L. Zerova, D.A. Firsov, G. Belenky, L. Shterengas, G. Kipshidze, T. Hosoda, S. Suchalkin, M. Kisin, 2010, published in Izvestiya Rossi-
iskoi Akademii Nauk. Seriya Fizicheskaya, 2010, Vol. 74, No. 1, pp. 78–80.
69
INTRODUCTION
The application of InGaAsSb/AlGaAsSb structures
with quantum wells in semiconductor lasers with
interband electron transitions allows the operator to
shift to a generation wavelength range of 3–4 μm.
Recombination processes in these structures to a large
extent determine the laser characteristics. In this
paper, we perform a comparative study of recombi-
nation processes in structures used earlier to create
lasers with record characteristics [1].
EXPERIMENTAL
Two types of structures containing four
In
0.54
Ga
0.46
As
0.24
Sb
0.76
quantum wells were studied.
The barriers were formed using solid solutions
Al
0.35
Ga
0.65
As
0.03
Sb
0.97
(type 1) and
In
0.25
Al
0.20
Ga
0.55
As
0.03
Sb
0.97
(type 2). The application
of quinary solid solution increases the capabilities of
optimizing the structure, which ensures improvement
of laser characteristics [2]. The time dependences of
photoluminescence for quantum energy correspond-
ing to the maximum photoluminescence signal were
studied in a broad temperature range of 77–300 K and
optical pumping intensity using the “up conversion”
method with a time resolution of about 1 ps.
Figure 1 shows the curves of the luminescence
decay for two types of structures measured at Т
0
=
300 K. The pumping conditions in these structures
differed considerably: in the first type of structure, the
width of the forbidden gap of the barrier for direct
transitions corresponded approximately to the
energy of the pumping radiation quantum ,
yielding a low absorption coefficient. In structures of
Γ
g
E
Γ
≅ ν
g
E h
the second type, , and the dynamic Burstein–
Moss effect was possible; this effect changes the
absorption coefficient of pumping radiation. In order
to correlate the value of the nonequilibrium electron
concentration with the pumping level, the depen-
dence of the photoluminescence intensity on the non-
equilibrium concentration was calculated. The results
from the calculations for Т
0
= 300 K and the corre-
sponding experimental dependences of the photolu-
minescence intensity in the maxima of the photolumi-
nescence decay curves on the pumping level are shown
in Fig. 2.
The dynamics of the initial segments is determined
by the processes of charge carrier capture in quantum
wells and the electron and hole energy relaxation pro-
cesses, including the influence of nonequilibrum opti-
cal phonons on these processes. The characteristic
times of the initial segments do not exceed 200 ps;
after this interval, the photoluminescence decay
dynamics is determined by the recombination pro-
cesses studied here.
The experimentally measured time dependences of
the photoluminescence signals and the known depen-
dences J
PL
in the maxima of the photoluminescence
decay curves on pumping level I
pump
made it possible to
calculate the dependence of the total recombination
rate on the concentration R(n
0
):
(1)
Γ
< ν
g
E h
pump
PL
pump PL
PL PL
pump pump
0
0
0
1
1 1
( )
1
.
dI
dn dJ
Rn
n dt I dJ dt
dJ dJ
I dI dt
-
- = =
=
Charge Carrier Recombination Mechanisms in Sb-Containing
Quantum Well Laser Structures
L. E. Vorob’ev
a
, V. L. Zerova
a
, D. A. Firsov
a
, G. Belenky
b
, L. Shterengas
b
, G. Kipshidze
b
,
T. Hosoda
b
, S. Suchalkin
b
, and M. Kisin
b
a
St. Petersburg State Polytechnical University, Polytechnicheskaya ul. 29, St. Petersburg, 195251 Russia
b
State University of New York, Stony Brook, New York, 11794 USA
e-mail: LVor@rphf.spbstu.ru
Abstract—The dynamics of interband luminescence in structures with InGaAsSb-based quantum wells and
barriers of different types was studied at different temperatures and excitation levels. The lifetime of optically
injected charge carriers in quantum wells at different temperatures and optical excitation levels was deter-
mined. An increased recombination rate in structures with deep electron quantum wells was discovered; it is
associated with the occurrence of resonance Auger recombination. It was concluded that the application of
quinary solid solutions as barriers in laser structures for a 3–4 μm wavelength range is to be preferred.
DOI: 10.3103/S1062873810010181