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Title: Effect of intraband carrier relaxation on the threshold characteristics of quantum well lasers

Abstract

The effect of intraband carrier relaxation on the threshold characteristics of InGaAsP quantum well (QW) lasers is studied. The dependence of the intraband hole-hole relaxation time {tau}{sub int} on temperature and carrier density is analyzed. It is shown that taking into account the finiteness of {tau}{sub int} and its dependence on temperature and carrier density strongly affects the gain and the threshold current density of QW lasers.

Authors:
; ; ; ;  [1]
  1. Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation), E-mail: zegrya@theory.ioffe.ru
Publication Date:
OSTI Identifier:
21088554
Resource Type:
Journal Article
Resource Relation:
Journal Name: Semiconductors; Journal Volume: 40; Journal Issue: 4; Other Information: DOI: 10.1134/S1063782606040208; Copyright (c) 2006 Nauka/Interperiodica; Article Copyright (c) 2006 Pleiades Publishing, Inc; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CARRIER DENSITY; CHARGE CARRIERS; HOLES; LASERS; QUANTUM WELLS; RELAXATION; RELAXATION TIME

Citation Formats

Kostko, I. A., Gun'ko, N. A., Bazhenov, N. L., Mynbaev, K. D., and Zegrya, G. G. Effect of intraband carrier relaxation on the threshold characteristics of quantum well lasers. United States: N. p., 2006. Web. doi:10.1134/S1063782606040208.
Kostko, I. A., Gun'ko, N. A., Bazhenov, N. L., Mynbaev, K. D., & Zegrya, G. G. Effect of intraband carrier relaxation on the threshold characteristics of quantum well lasers. United States. doi:10.1134/S1063782606040208.
Kostko, I. A., Gun'ko, N. A., Bazhenov, N. L., Mynbaev, K. D., and Zegrya, G. G. Sat . "Effect of intraband carrier relaxation on the threshold characteristics of quantum well lasers". United States. doi:10.1134/S1063782606040208.
@article{osti_21088554,
title = {Effect of intraband carrier relaxation on the threshold characteristics of quantum well lasers},
author = {Kostko, I. A. and Gun'ko, N. A. and Bazhenov, N. L. and Mynbaev, K. D. and Zegrya, G. G.},
abstractNote = {The effect of intraband carrier relaxation on the threshold characteristics of InGaAsP quantum well (QW) lasers is studied. The dependence of the intraband hole-hole relaxation time {tau}{sub int} on temperature and carrier density is analyzed. It is shown that taking into account the finiteness of {tau}{sub int} and its dependence on temperature and carrier density strongly affects the gain and the threshold current density of QW lasers.},
doi = {10.1134/S1063782606040208},
journal = {Semiconductors},
number = 4,
volume = 40,
place = {United States},
year = {Sat Apr 15 00:00:00 EDT 2006},
month = {Sat Apr 15 00:00:00 EDT 2006}
}
  • Intraband relaxation time, which causes spectral broadening of optical gain and spontaneous emission spectra, is estimated theoretically for quantum-well lasers. Carrier-carrier and carrier-longitudinal optical (LO) phonon scattering mechanisms are considered, and it is shown that hole-hole electron-hole, and hole-LO phonon scattering are dominant in spectral broadening. Intraband relaxation time determined by all of these mechanisms increases slightly with the decrease of well width. Dependence of intraband relaxation time on temperature, carrier density, and energy of electron and hole is also shown. Spectral line shape is discussed as an extension of the above calculation and an approximated formula is given.
  • Influence of the free carrier component due to the plasma effect on carrier-induced refractive index change and its dependency on polarization for multiple-quantum-well (MQW) and bulk lasers are experimentally studied. The ratios of the component to the total index change, R[sub fc], are 0.6, 0.4, and 0.1 for the 1.3-[mu]m MQW, 1.3-[mu]m bulk, and 0.8-[mu]m MQW lasers, respectively. The TM/TE polarization ratios of the component, R[sub TM/TE], are 0.8 and 0.3 for 1.3-[mu]m MQW and 0.8-[mu]m MQW lasers. The relationship between the index change and the carrier overflow (to barrier and separate confinement heterostructure layers) for MQW lasers is alsomore » discussed. Large R[sub fc] and R[sub TM/TE] for the 1.3-[mu]m MQW laser result from the carrier overflow.« less
  • The Auger recombination effect on the threshold current of the InGaAsP quantum well (QW) laser is studied theoretically. All possible transitions between the quantized subbands of two-dimensional carriers are taken into account in evaluating the radiative process with the k-selection rule and the Auger process. The calculated threshold current agrees well with the reported experimental results for 1.07 ..mu..m InGaAsP QW lasers. The Auger component of the threshold current and its temperature dependence strongly depend on the QW structure, resulting in the necessity for an elaborate QW structure design, although both cannot be optimized at the same time. A designmore » procedure is elucidated for a structure which gives the lowest threshold current density for the 1.07, 1.3, and 1.55 ..mu..m InGaAsP QW lasers.« less
  • A comprehensive study of the effect of compressive strain on the threshold current performance of long-wavelength (1.5 [mu]m) quantum well (QW) lasers is presented. Model predictions of threshold currents in such devices identify QW thickness as a parameter that must be considered in optimizing laser performance when Auger currents are present. A minimum in threshold current density is thus calculated when QW thicknesses are maintained between 70 and 100 [angstrom], presently achieved in strained QW's using InGaAsP, and thereby isolating strain effects from any thickness and energy dependences. Experimental comparisons between strained and unstrained devices thus reveal strain-induced reductions inmore » internal transparency current density per QW from 66 to 40 A/cm[sup 2], an increase in peak differential modal gain from 0.12 to 0.23 cm/A, and evidence for the elimination of intervalence band absorption as compressive strain increases from 0 to 18%. However, most of these improvements arise in the first [approximately]1% of compressive strain. In order to fabricate low-threshold 1.5 [mu]m buried heterostructure BH devices in InP using these trained QW active regions, an optimized design is derived which shows that threshold current is at its lowest when the strip width is approximately 0.6-0.7 [mu]m. Example uncoated BH lasers exhibit room temperature pulsed threshold currents of 5.9 mA in structures without current blocking layers, and 4.1 mA in structures with current blocking layers.« less
  • Calculations are made of the threshold characteristics and transverse dimensions of a luminous spot for a laser pumped by a sharply focused electron beam. The calculations involve jointly solving equations for the electromagnetic field and the active particles. It is found that for small diameters of the electron beam, the excitation threshold and size of the lasing zone are governed by electron scattering during slowing down and diffusion of carriers across the resonator axis. A comparison is made of the results of these calculations with the experiment.