Effective Green Semiconductor Lasers With Multiple CdSe/ZnSe QD
Active Region for Electron Beam Pumping.
Gronin S.V.1, Zverev M.M.2, Sorokin S.V.1, Sedova I.V.1, Gamov N.A.2,
Peregoudov D.V.2, Studionov V.B.2, Kop’ev P.S.1 and Ivanov S.V.1
1
Ioffe Physico-Technical Institute of RAS, Polytekhnicheskaya 26, St. Petersburg 194021,
Russia
2
Moscow Institute for Radio Engineering, Electronics and Automation, Vernadskogo 78,
Moscow 119454, Russia
Efficiency, %
Electron beam pumped (EBP) semiconductor lasers using ZnSe-based structures as active
elements look very promising for the development green lasers because of no requirements of
both p-n junction and low-resistivity contacts. Another advantage of EBP lasers is that the
maximum conversion efficiency of electron beam energy to light is of ~30%. The possibility
of using ZnSe-based quantum-size heterostructures for EBP green lasers demonstrated during
last decade. Thus, room-temperature lasing at Ee<5keV and extremely low threshold current
density jth=0.4-0.5 A/cm2 (at Ee=8-10keV) have been demonstrated in laser heterostructures
with short-period superlattice (SL) waveguide and single CdSe/ZnSe quantum dot (QD)
active region [1]. The structure with three ZnSe/CdSe QD sheets arranged within 0.4um-thick
extended SL waveguide has demonstrated laser generation with efficiency (per one facet) as
high as ~4% [2].
Here we present the latest results on fabrication and study of ZnSe-based EBP laser
heterostructure with multiple CdSe/ZnSe QD sheets. Laser heterostructure has been grown by
molecular beam epitaxy pseudomorphically to GaAs (001) substrate and consists of 1.6mthick ZnMgSSe cladding, active region with ten CdSe/ZnSe QD sheets equally spaced within
a 0.6um-thick ZnSe/ZnSSe SL waveguide and cap 20-nm ZnMgSSe layer. The nominal
thickness of CdSe QD layers was chosen to ~2.5
monolayers. All measurements were carried out at
9
L=0.46 мм
8
room temperature in transverse excitation
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geometry in pulse mode at electron beam energy
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Ee=10-30 keV. The lasing has been observed at the
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4
wavelength of ~542nm (T=300K) with FWHM of
3
the emission line of ~2-3 nm. The maximum
2
achieved values of pulse output power ~12W per
1
facet has been registered at Ee=23keV. Maximum
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18
20
22
24
26
Electron beam energy, keV
quantum efficiency of ~8.5% per facet has been
obtained at the same electron beam energy and
Fig.1 The dependence of maximum emission
efficiency on electron beam energy
electron beam current Ie~5.7mA. The main reason
of increase of laser efficiency seems to be more
effective utilization of pumping energy by means of adjustment of both structure geometric
parameters and electron beam penetration depth into the sample. Further increase of light
output power is likely can be achieved by increasing Ie keeping constant electron beam energy
Ee. The question on optimum number of active CdSe QD layers will be discussed. This work
was partly supported by FASI Contract and ISTC Project No. 3754.
[1]M. M. Zverev, N. A. Gamov, E. V. Zhdanova, D. V. Peregudov, V. B. Studenov, S. V.
Ivanov, I. V. Sedova, S. V. Sorokin, S. V. Gronin and P. S. Kop’ev, Tech. Phys. Lett.
33(12), 1032 (2007).
[2]M.M. Zverev, S.V. Sorokin, I.V. Sedova, S.V. Ivanov, D.V. Peregudov, P.S. Kop’ev,
Phys. Stat. Sol. (c) 2, 923 (2005)