The Influence of the Parameters of a Short-Period InGaAs/InGaAlAs Superlattice on Photoluminescence Efficiency
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fluence of the Parameters of a Short-Period InGaAs/InGaAlAs Superlattice on Photoluminescence Efficiency S. S. Rochasa*, I. I. Novikova, A. G. Gladysheva, E. S. Kolodeznyia, A. V. Babicheva, V. V. Andryushkina, V. N. Nevedomskiib, D. V. Denisovc, L. Ya. Karachinskya, A. Yu. Egorovd, and V. E. Bougrova a
ITMO University, St. Petersburg, 197101 Russia Research Center “Materials Science and Characterization in Advanced Technology”, Ioffe Institute, St. Petersburg, 194021 Russia c St. Petersburg Electrotechnical University “LETI”, St. Petersburg, 197376 Russia d Connector Optics LLC, St. Petersburg, 194292 Russia *e-mail: [email protected]
b Joint
Received June 11, 2020; revised July 23, 2020; accepted August 4, 2020
Abstract—We have studied heterostructures based on short-period InGaAs/InGaAlAs superlattices (SLs) manufactured by molecular-beam epitaxy on InP substrates, intended for use as active regions in verticalcavity surface-emitting lasers operating in a 1.3-μm spectral range. The heterostructures were characterized by measuring photoluminescence (PL) emission and X-ray diffraction. It is established that variation of the ratio of quantum-well and barrier-layer thicknesses in the SL allows controlled shift of the PL peak position for lasing in the 1.3-μm range at almost constant PL efficiency. Keywords: vertical-cavity surface-emitting laser, active region, superlattice, quantum well, molecular-beam epitaxy. DOI: 10.1134/S1063785020110267
In recent years, progress in the field of semiconductor lasers has been related mostly to the improvement of their active region—a medium responsible for the optical gain. Reduction of the lasing threshold current due to decreased dimensionality of the active region led to a drop in the maximum optical gain in laser heterostructures and saturation of the gain at high current densities, which made lasing impossible when optical losses exceeded the level of saturated optical gain. Increasing the gain by using several quantum wells (QWs) [1] or an array of quantum dots (QDs) [2] did not always ensured lasing, particularly in vertical-cavity surface-emitting lasers (VCSELs), in which (unlike lasers of ridge design operating in the 1.3-μm range), the efficiency of overlap of the region of optical gain due to standing light wave generated in the laser cavity was decreased. The use of a short-period superlattice (SL) as the active region of VCSELs operating in the 1.3-μm range can provide an effective alternative to activeregion heterostructures with QW and QD arrays [3]. In these heterostructures, the active region consists of repeated pairs of semiconductor QW/barrier layers of InGaAs/InGaAlAs, in which the gain is achieved due
to the injection pumping and interaction with a standing wave of the short-period SL. In contrast to the traditional heterostructures based on QWs and QDs, heterostructures with short-period SLs form a miniband [4] involving both the QW and barrier-layer regions, which makes the width of the effective part of the active region twice as large as th
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