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Title: Emission spectra of a laser based on an In(Ga)As/GaAs quantum-dot superlattice

The spectral characteristics of a laser with an active region based on a ten-layer system of In(Ga)As/GaAs vertically correlated quantum dots with 4.5-nm GaAs spacer layers between InAs quantum dots are studied under the conditions of spontaneous and stimulated emission, depending on the current and the duration of pump pulses. Data obtained by transmission electron microscopy and electroluminescence and absorption polarization anisotropy measurements make it possible to demonstrate that the investigated system of tunnel-coupled InAs quantum dots separated by thin GaAs barriers represents a quantum-dot superlattice. With an increase in the laser pump current, the electroluminescence intensity increases linearly and the spectral position of the electroluminescence maximum shifts to higher energies, which is caused by the dependence of the miniband density-of-states distribution on the pump current. Upon exceeding the threshold current, multimode lasing via the miniband ground state is observed. One of the lasing modes can be attributed to the zero-phonon line, and the other is determined by the longitudinal-optical phonon replica of quantum-dot emission. The results obtained give evidence that, under conditions of the laser pumping of an In(Ga)As/GaAs quantum-dot superlattice, strong coupling between the discrete electron states in the miniband and optical phonons takes place. This leads tomore » the formation of quantum-dot polarons, resulting from the resonant mixing of electronic states whose energy separation is comparable to the optical-phonon energy.« less
Authors:
; ; ; ; ; ; ;  [1]
  1. Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation)
Publication Date:
OSTI Identifier:
22469721
Resource Type:
Journal Article
Resource Relation:
Journal Name: Semiconductors; Journal Volume: 49; Journal Issue: 10; Other Information: Copyright (c) 2015 Pleiades Publishing, Ltd.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 77 NANOSCIENCE AND NANOTECHNOLOGY; ABSORPTION; DENSITY OF STATES; ELECTROLUMINESCENCE; ELECTRONS; EMISSION SPECTRA; GALLIUM ARSENIDES; GROUND STATES; INDIUM ARSENIDES; LANTHANUM SELENIDES; LAYERS; PHONONS; POLARIZATION; POLARONS; QUANTUM DOTS; SEMICONDUCTOR LASERS; STIMULATED EMISSION; SUPERLATTICES; THRESHOLD CURRENT; TRANSMISSION ELECTRON MICROSCOPY