Advanced Electronic Technologies and Systems Based on Low-Dimensional Quantum Devices

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3. High Technology - Vol. 42

Advanced Electronic Technologies and Systems Based on Low-Dimensional Quantum Devices

edited by

Minko Balkanski Universite Pierre et Marie Curie, Paris, France

and

Nikolai Andreev Technical University of Sofia, Sofia, Bulgaria

Springer-Science+Business Media, BV

Proceedings of the NATO Advanced Study Instute on Advanced Electronic Technologies and Systems Based on Low-Dimensional Quan­tum Devices Sozopol, Bulgaria 18-28 September 1996

A C.I.P. Catalogue record for this book is available from the Library of Congress.

ISBN 978-90-481-4964-3 ISBN 978-94-015-8965-9 (eBook) DOI 10.1007/978-94-015-8965-9

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Softcover reprint of the hardcover 1 st edition 1997

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TABLE OF CONTENTS

Preface

Acknowledgments

1. Fnndamentals on Quantum Structures for Electro-Optical

Devices and Systems

1.1 Electron State Symmetries and Optical Selection Rilles in the

(GaAs)m(AIAs)n Superlattices Grown Along the [001], [110], and [111]

Directions.

Yu. E. Kitaev, A. G. Panfilov, P. TroncandR. A. Evarestov

1.1.1 Electronic Structure of AlAs/GaAs Superlattices with an

Embedded Centered GaAs Quantum Well.

V. Donchev, Tzv. Ivanov andK. Gennanova

1.1.2 Electronic States in Graded Composition Quantum Wells under a

Constant Electric Field.

S. Vlaev, A. Miteva and V. Don<.:hev

1.1.3 Dimension Related Effects on the Structure Perfection in Si/SiC

Milltilayer Structures.

Xl

XIX

51

55

E. Valcheva, T. Paskova, O. Kordina, R. Yakimova, E. Janzen 59

1.1.4 Effect of the Non-Parabolicity and Dynamical Screening on the

Second-Hannonic Generation in Doubly Resonant Asymmetric

Quantum Well Structures.

M. Zaluzny and V. Bondarenko 63

1.1.5 Optical Diagnostics of Quantum Dots in GaAsIlnxGal_xAs

Heterostructures.

V. Ya. Aleshkin, V. M. Danil'tsev, O. I. Khrykin, Z. F.

Krasil'nik, D. G. Revin, V. I. Shashkin 65

1.1.6 Generation of High - Frequency Oscillations by Electromagnetic

VI

Shock Wave (EMSW) in Nonlinear Transmission lines on the Basis of

Multilayer Heterostructures.

A. B. Kozyrev and A. M. Belyantsev 67

1.1.7 Picosecond Spectroscopy Studies of CuS and CuInS2 Quantum

Dots with Chemically Modified Surface.

A. M. Malyarevich, K. V. Yumashev, P. V. Prokoshin, M. V.

Artemyev, V. S. GurinandV. P. Mikhailov

1.1.8 Intensity Induced Polarization Rotation due to Cascading in

ImbalancedType II Nearly Phase Matched Frequency Doubling.

69

S. Saltiel, I. Buchvarov, K. Koynov, P. Tzankov and Ch. Iglev 71

1.2 Modeling Quantum Well Laser Diode Structures.

P. Blood, D.L. Foulger and P.M. Smowton 77

1.2.1 Silicium Crystal Photoluminescence as Transducer for

Biosensors.

N. F. Starodub, L. L. Fedorenko, V. M. Starodub, S. P. Dikij 91

1.2.2 Injection Lasers based on Vertically Coupled Quantum Dots.

A. E. Zhukov, V. M. Ustinov, A. Yu. Egorov, A. R. Kovsh,

N. N. Ledentsov, M. V. Maksimov, A. F. Tsatsul'nikov, N.

Yu. Gordeev, S. V. Zaitsev, P. S. Kop'ev.

1.2.3 Infrared Emission of Hot Holes in Strained Multi-Quantum­

Well Heterostructures InGaAs/GaAs under Real Space Transfer.

V. Ya. Aleshkin, A. A. Andmnov, A. V. Antonov, N. A.

Bekin, V. I. Gavrilenko, D. G. Revin, E. R. Lin'kova, I. G.

93

Matkina, E. A. Uskova andB. N. Zvonkov 97

1.3 Microcavity Semiconductor Lasers

J. G. McInerney, Damien P. Courtney, Peter M. W. Skovgaard arrl

Brian Corbett 99

2. MQW Optoelectronic Devices and Systems

2.1 Exciton Absorption Saturation and Camer Transport in Quantum

Well Semiconductors.

A. Miller, T. M. Holden, G. T. Kennedy, A. R. Cameron and P.

VII

Riblet 117

2.2. IntegratedOptoelectronics - the Next Technological Revolution.

A.S. Popov 137

2.3. Opportunities of Vertical - Cavity - Surface - Emitting Lasers

(VCSEL) in display and optical communication systems.

A.S. Popov 155

2.4. New Integrated Photoreceiver Systems - Charge Coupled Devices

(CCD).

A.S.Popov 175

2.5. Optical Switches and Modulators for Integrated Optoelectronic

Systems.

A.S.Popov 189

2.5.1 Scalar Off-Resonant Modulation Instabilities in Genernl

Rare-Earth Doped Fiber Amplifying Devices.

T. Mirtchev 201

2.5.2 Quantum Dot Laser With High Temperature Stability of

Threshold Current Density.

A.R. Kovsh, A.E. Zhukov, M.A. Odnoblyudov, A. Yu.

Egorov, Y.M. Ustinov, N.N. Ledentsov, M.Y. Maksimov,

A.F. Tsatsul'nikov, N. Yu. Gordeev, S.Y. Zaitsev and P.S.

Kop'ev 207

VJ1l

3. Soliton-Based Switching, Gating and Transmission

Systems

3.1 Soliton-Based Logic Gates and Soliton Transmission Systems.

A. D. Boardman,R. Putman andK. Xie 209

3.1.1 100 GHz * 100 km Optical Soliton Data Transmission

System, Basedon Gradient Distributed Er3+ - Doped Fiber Amplifiers.

T. Mirtchev 267

3.1.2 Control of Lightguiding in H:LiTa03 and H:LiNb03 Thin

Films.

C. C. Ziling, V. V. Atuchin, I. Savatinova, S. Tonchev, M. N.

Armenise and V. N. Passaro 277

3.1.3 Self - Phase Modulation due to Third-Order Cascading:

Application to All-Optical Switching Devices.

S. Tanev,K. Koynov, S. Saltiel, K. XieandA. D. Boardman 281

Index 289

NA TO ASI held in Sozopol, Bulgaria, September 18-28, 1996

ADVANCED ELECTRONIC TECHNOLOGIES AND SYSTEMS BASED

ON LOW -DIMENSIONAL QUANTUM DEVICES

Sponsored by

NATO Scientific and Environmental Affairs Division

Ministere de I 'Enseignement Superieur et de la Recherche, France

Universite Pierre et Marie Curie, Paris, France

University St. Kliment Ohridski, Sofia, Bulgaria

Technical University, Sofia, Bulgaria

Institut des Hautes Etudes pour Ie development de la Culture, de la Science et

de la Technologie en Bulgarie, Paris, France.

Principal School Support NATO Program for Priority on High Technology

Bulbank, Bulgarian Bank for Foreign Trade, Sofia, Bulgaria

Universite Pierre et Marie Curie, Paris, France

IX

PREFACE

This volume on Advanced Electronic Technologies and Systems based on Low­

Dimensional Quantum Devices closes a three years series of NATO - AS!' s.

The first year was focused on the fundamental properties and applications. The second year

was devoted to Devices Based on Low-Dimensional Semiconductor Structures. The third year is

covering Systems Based on Low-Dimensional Quantum Semiconductor Devices.

The three volumes containing the lectures given at the three successive NATO - ASI's

constitute a complete review on the latest advances in semiconductor Science and Technology

from the methods of fabrication of the quantum structures through the fundamental physics am basic knowledge of properties and projection of performances to the technology of devices and

systems.

In the first volume: " Fabrication, Properties and Application of Low Dimensional

Semiconductors" are described the practical ways in which quantum structures are produced, the

present status of the technology, difficulties encountered, and advances to be expected. The basic

theory of Quantum Wells, Double Quantum Wells and Superlattices is introduced and the

fundamental aspects of their optical properties are presented. The effect of reduction of

dimensionality on lattice dynamics of quantum structures is also discussed.

In the second volume: " Devices Based on Low Dimensional Structures" the fundamentals

of quantum structures and devices in the two major fields: Electro-Optical Devices and

Pseudomorphic High Eectron Mobility Transistors are extensively discussed.

Xl

Xll

In the third volume: " Advanced Electronics Technology and Systems Based on Low -

Dimensional Quantum devices ", which we present now, the major developments in Quantum

Structures Systems are discussed in three main chapters:

Fundamentals on Quantum Structures for Electro-Optical Devices and Systems

MQW Optoelectronic Devices and Systems

Soliton-Based Switching, Gating and Transmission Systems

Fundamentals on Quantum Structures for Electro-Optical Devices and Systems

As an example of the recent development in basic research the first chapter is devoted to

Electron State Symmetries and Optical Selection Rules in the (GaAs)m(AIAs)n Superlattices

Grown Along the [001], [110], and [111] Directions. Using the method of induced band

representations of space groups, the full electron state symmetries and the selection rules for

optical transitions in the (GaAs)m(AlAs)n superlattices (SL's) are studied.

The (GaAs)m(AlAs)n [hkl] SL's are a new class of artificially grown crystals whose

structure (i. e. a space group G and an arrangement of atoms over the Wyckoff positions in a

primitive cell) depends on the growth direction [hkl] and numbers of monolayers (m, n) of

constituent materials.

For each direction of growth, these SL's constitute several single crystal families specified

by different space groups Gl' G2' ... Gr By definition, within each family, the crystals have the

same space group Gi but differ from each other by an arrangement of atoms over the Wyckoff

positions. Thus, from the crystallographic point of view, the SL's with different numbers of

monolayers m and n are distinct crystals, even those belonging to the same family.

Such a dependence of the SL crystal structure on the numbers of monoloyers influences on

the phonon and electron states in these crystals. To study the optical properties of SL's one

X III

should know the complete information on their crystal structure.

Knowledge of the optical properties are essential for modeling quantum well laser diode

structures. Many of interactions of quantum wells in lasers derive from the properties of the

density of states function of the two-dimensional electron system. The abrupt edge of the density

of states as a function of energy provides a very high differential gain above transparency leading

to significant reductions in threshold current in appropriately designed devices compared with their

bulk counterparts. In all quantum well lasers the threshold current follows the intrinsic linear

dependence over a low temperature region but as the temperature is increased an approximately

exponential increase in threshold with temperature is superimposed on the linear behavior and this

becomes dominant at sufficiently high temperature. The additional current above the intrinsic

linear component is often referred as the " excess current". Experiments have shown that this

current is chiefly due to non-radiative recombination via deep states in the AlGaAs barrier material

forming the core of the waveguide which contains a higher density of deep states than the GaAs

material comprising the well. Because the carrier density in the barrier increases exponentially

with temperature compared with that in the well, this excess current component has an

exponential temperature dependence.

For visible emitting lasers it is often not sufficient to consider the active region of the

quantum well in isolation from the rest of the device structure. Realistic estimate of the threshold

current, particularly its temperature dependence should include current paths in other parts of the

device structure.

Examine of possible current paths and different assumptions on the physical parameters

leads to the conclusion that the best approach to modeling the current through a laser is a self­

consistent simulation of the current flow and potential by numerical solution of the current

continuity equations and Poisson's equation throughout the complete structure, together with the

solution of Schrodinger's equation for a non-square well. Such simulation for 670 urn GaInP

XIV

lasers are presented in detail in this volume. The results give a good description of the temperature

dependence of threshold current and provide tutorial illustrations of the inadequacies of the simple

flat - band model.

An other important feature for the systems based on quantum structure devices are the

Microcavity Semiconductor Lasers. In the chapter on Microcavity Semiconductor Lasers the

theory and recent experimental developments in such lasers and their implications are reviewed.

Particular attention is paid to microdisk lasers which support whispering gallery modes.

InGaAsP/1nP microdisks have recently been pumped optically, resulting in the fist achievement

of ew room temperature lasing in these devices.

The future viability of optoelectronics as a mainstream technology in communications,

computing, data storage and consumer products is contingent on developing efficient, flexible and

controllable photonic emitters, detectors, filters, amplifiers, memory elements and logic devices.

It is intriguing and exiting to consider utilizing the quantum nature of light itself in designing am studing photonic devices of all types. A critical part of this effort is the study of wavelength scale

structures for control and selection of photon modes; structures such as microcavities and the

closely related photonic bandgap materials.

A microcavity laser may be defined operationally as one whose cavity length is comparable

to the emission wavelength, in at least one dimension. A simple example is the planar

microcavity laser whose thin (::::1..) active region is bounded by two parallel, highly reflecting

mirrors. A related structure is the vertical cavity surface - emitting laser (VeSEL) in which a

planar microcavity is modified (by implantation, oxidation, etching or optical pumping) so that

the gain is of limited spatial extent: the cavity is only a few wavelengths long but much larger in

lateral extent.

From a physical point of view, a microcavity may be considered as an atom or atom-like

xv

emitter inside a cavity. In a true microscopic system the dimensions are comparable to the size of

the atom and are thus much smaller than the (optical) wavelength. In a macroscopic system the

dimensions are much greater than the wavelength. A microcavity is therefore a mesoscopic

system, in that its scale is intermediate between those of microscopic and macroscopic objects.

Because of this scaling, it is often possible to adopt a semi-classical point of view, in which the

active atom or atom-like species (in this case the coupled system consisting of an electron in the

conduction band of the semiconductor and the corresponding hole in the valence band) is treated

quantum mechanically and the electromagnetic field is considered classically. From an engineering

or applied - physics perspectives, a microcavity may be considered as a filter or distributor of the

radiation from the aton:..

In the chapter on microcavity lasers the discussion is based on the microdisk laser, in

which light undergoes total internal reflection along the perimeter of an isolated circular disk,

where two-dimensional mode confinement is provided via so-called « whispering gallery modes ».

After a section which outlines some theoretical and fundamental considerations,

particularly regarding the predicted effects of l-D and 2-D microcavities on the density of photon

modes. The fabrication of typical microdisk lasers, recent optical pumping experiments and the

first demonstration of CW room temperature lasing semiconductor microdisk laser are described

and discussed.

MQW Optoelectronic Devices and Systems

Optoelectronic devices are first discussed in a chapter on Exciton Absorption Saturation

and Carrier Transport in quantum Well Semiconductors. Optical nonlinearities associated with

excitonic absorption features in multiple quantum well (MQW) semiconductors offer a number of

useful functions for optoelectronics devices. These include laser mode-locking elements, saturable

elements for controlling the propagation of optical solutions in fibre transmission systems, all-

XV}

optical directional coupler switches and self-electro-optic devices for communications, signal

processing and computing. The operation and optimization of these devices rely on an

understanding of the mechanisms which contribute to absorption saturation and the motion of

optically generated electrons and holes in directions both parallel and perpendicular to the quantum

wells. The chapter on Exciton Absorption Saturation and Carrier Transport in quantum Well

Semiconductors reviews measurements of exiton absorption saturation mechanism and transport

processes (in-well and cross-well) relevant to new optoelectronic electro-optic and nonlinear

optical devices.

Resonant nonlinear and electro-optic interactions are particularly large in quantum wells at

room temperature because of prominent excitonic features in their absorption spectra close to the

band gap energy. Absorption coefficients at the peak of the exciton absorption can be in excess of

104 em -1 providing very efficient absorption in samples only a few microns thick. Optical

excitation of excitons and free carriers can bleach these absorption features by a number of

mechanisms including phase space filling, Coulomb screening and lifetime broadening. Pump­

probe measurements using ultrashort pulses of laser light with different linear and circular

polarizations can be used to identify the relative magnitudes of the various contributions.

After creation of the electron and hole pairs, a dynamical situation is produces whereby the

bleaching will relax because of the motion and recombination processes for the free carriers in the

sample. Drift and diffusion properties normally determine the manner in which semiconductor

devices operate but many additional processes in MQW structures have to be considered if we

wish to assess the ultimate performance limits of low dimensional devices. These processes

include thermionic emission from, tunneling through, and trapping into the wells. The ability to

control the motion of electrons and holes by designing the structures to make use of these

processes gives opportunities for engineering devices with new and unique properties. Pump­

probe and transient grating techniques can be used to monitor the motion and dynamics of the

carriers on ultrashort time scales using excitonic saturation nonlinearities as the probe.

XVll

Soliton-Based Switching, Gating and Transmission Systems

A large chapter in this volume is devoted to the soliton - based logic gates and soliton

transmission systems. This chapter is a glance into the future since solitons can be considered as

candidates as ''information bits" in telecommunication systems behind the year 2000.

The volume contains also a certain number of short original contributions showing the

present status of the art in quantum systems.

M. BALKANSKI

N. ANDREEV

Acknowledgments

The NATO Advanced Study Institute on "Advanced Electronic Technologies and Systems

based on Low-Dimensional Quantum Devices", held in Sozopol, Bulgaria, September 18-28,

1996, was made possible by an award from the Assistant Secretary General for Scientific and

Environmental Mfairs. We are particularly grateful to Dr. J.A. Rausell-Colom, Program Director

for Priority Area and High technology, for his constant interest and helpful guidance during the

preparation of the AS!.

Of great value for the present success of this school and the future development of a Center

for Scientific Culture in Bulgaria is the personal involvement of Dip. Eng. Peter Kimenov,

General Manager of Administration Department of Bulbank and that of Dichko Fotev,

Administrator of the Sozopol Pochivna Basa of Bulbank.

We owe special thank to the rector of Sofia University, Professor Ivan Lalov, who not

only supported very generously the whole process of the organization of the school, but also

came to Sozopol to attest with his presence his personal interest in the development of scientific

culture in Bulgaria. Many colleagues from Sofia University and from the Technical University

have generously helped the organization of the school and we are grateful for their involvement.

We also wish to thanks Dr. Stoyan Tanev for giving so much of his energy mxl

enthusiasm to the enterprise. Lucy Nedialkova has also generously helped the preparation of the

book based on the lectures of the School.

xix