Optical Properties of Semiconductors

188 Pages·1976·5.856 MB·English

by  N. G. Basov (auth.), N. G. Basov (eds.)

OPTICAL PROPERTIES OF SEMICONDUCTORS
OPTICHESKIE SVOISTV A POLUPROVODNIKOV
OnTHQECHHE CBOMCTBA
nOnYnpOBO~HHHOB
The Lebedev Physics Institute Series
Editors: Academicians D. V. Skobel'tsyn and N. G. Basov
P. N. Lebedev Physics Institute, Academy of Sciences of the USSR
Recent Volumes in this Series
Volume 35 Electronic and Vibrational Spectra of Molecules
Volume 36 Photodisintegration of Nuclei in the Giant Resonance Region
Volume 37 Electrical and Optical Properties of Semiconductors
Volume 38 Wi~eband Cruciform Radio Telescope Research
Volume 39 Optical Studies in Liquids and Solids
Volume 40 Experimental Physics: Methods and Apparatus
Volume 41 The Nucleon Compton Effect at Low and Medium Energies
Volume 42 Electronics in Experimental Physics
Volume 43 Nonlinear Optics
Volume 44 Nuclear Physics and Interaction of Particles with Matter
Volume 45 Programming and Computer Techniques in Experimental Physics
Volume 46 Cosmic Rays and Nuclear Interactions at High Energies
Volume 47 Radio Astronomy: Instruments and Observations
Volume 48 Surface Properties of Semiconductors and Dynamics of Ionic Crystals
Volume 49 Quantum Electronics and Paramagnetic Resonance
Volume 50 Electroluminescence
Volume 51 Physics of Atomic Collisions
Volume 52 Quantum Electronics in Lasers and Masers, Part 2
Volume 53 Studies in Nuclear Physics
Volume 54 Photomesic and Photonuclear Reactions and Investigation Methods with Synchrotrons
Volume 55 Optical Properties of Metals and Intermolecular Interactions
Volume 56 Physical Processes in Lasers
Volume 57 Theory of Interaction of Elementary Particles at High Energies
Volume 58 Investigations in Nonlinear Optics and Hyperacoustics
Volume 59 Luminescence and Nonlinear Optics
Volume 60 Spectroscopy of Laser Crystals with Ionic Structure
Volume 61 Theory of Plasmas
Volume 62 Methods in Stellar Atmosphere and Interplanetary Plasma Research
Volume 63 Nuclear Reactions and Interaction of Neutrons and Matter
Volume 64 Primary Cosmic Radiation
Volume 65 Stellarators
Volume 66 Theory of Collective Particle Acceleration and Relativistic Electron Beam Emission
Volume 67 Physical Investigations in Strong Magnetic Fields
Volume 68 Radiative Recombination in Semiconducting Crystals
Volume 70 Group-Theoretical Methods in Physics
Volume 72 Physical Acoustics and Optics: Molecular Scattering of Light; Propagation of Hypersound; Metal Optics
Volume 73 Microwave-Plasma Interactions
Volume 75 Optical Properties of Semiconductors
In preparation
Volume 69 Nuclear Reactions and Accelerators of Charged Particles
Volume 71 Photonuclear and Photomesic Processes
Volume 74 Neutral Current Sheets in Plasmas
Volume 76 Lasers and Their Applications
Volume 77 Submillimeter and X-Ray Telescopes and Radiotelescopes
Volume 78 Research in Plasmas From Molecular Lasers
Volume 79 Luminescence Centers in Crystals
Volume 80 Synchrotron Radiation
Volume 81 Pulsed Gas-Discharge Lasers with Atomic and Molecular Transitions
Proceedings (Trudy) of the P. N. Lebedev Physics Institute
Volume 75
OPTICAL PROPERTIES
OF SEMICONDUCTORS
Edited by
N. G. Basov
P. N. Lebedev Physics Institute
Academy of Sciences of the USSR
Moscow, USSR
Translated from Russian by
Albin Tybulewicz
Editor: Soviet Physics-Semiconductors
CONSULTANTS BUREAU
NEW YORK AND LONDON
Library of Congress Cataloging in Publication Data
Main entry under title:
Optical properties of semiconductors.
(proceedings (Trudy) of the P. N. Lebedev Physics Institute; v. 75)
Translation of Opticheskie svolstva poluprovodnikov.
Half title also in Russian.
"A special research report."
Includes bibliographical references.
1. Semiconductors-Optical properties-Addresses, essays, lectures. 2. Excitons-
Addresses, essays, lectures. I. Basov, Nikolai' Gennadievich, 1922- II. Series:
Akademiia nauk SSSR. Fizicheskii' institut. Proceedings; v. 75.
QC1.A4114 vol. 75 [QC61 1.6.06] 530'.08s [537.6'22]
75-37609
The original Russian text was published by Nauka Press in Moscow in 1974 for the
Academy of Sciences of the USSR as Volume 75 of the Proceedings of the P. N.
Lebedev Physics Institute. This translation is published under an agreement with the
Copyright Agency of the USSR (V AAP).
ISBN 978-1-4615-7550-4 ISBN 978-1-4615-7548-1 (eBook)
DOl 10.1007/978-1-4615-7548-1
© 1976 Consultants Bureau, New York
A Division of Plenum Publishing Corporation
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CONTENTS
Radiation Emitted from Semiconductor Lasers
in Strong Magnetic Fields and under High
Hydrostatic Pressures
I. I. Zasavitskii
Introduction ....................................... 1
e .•••••••
Chapter I
Influence of Magnetic Fields and High Pressures on Energy Spectra of
Semiconductors ............................................ . 5
§ 1. Influence of Magnetic Fields on Energy Structure of III-V and
IV -VI Semiconductor Compounds •••••••••.••.•.•.•••.••...• 5
§2. Influence of Pressure on Energy Structures of III-V and IV-VI
Compounds . . . . . . . . . . . . . . . . . . . . . ~ . . . . . . . . . . . . . . . . . . . 11
§ 3. Characteristics of Semiconductor Laser Operation Affected by
Variation of Temperature, Pressure, and Magnetic Field •••••••••• 13
Chapter II
Experimental Method ..........•............................. 16
§ 1. Apparatus for Excitation of Injection Lasers and Recording of
Emission Spectra .................. ................... . 16
§ 2. Q-Switched CO2 Laser .............•................... II 19
§ 3. Technique Used in Low-Temperature Magnetooptic Investigations at
Infrared Wavelengths ................................. . 20
§4. Apparatus Used in Optical Measurements at Infrared Wavelengths
under High Hydrostatic Pressures at 77°K ••••.•.......•..•••. 23
§ 5. Zinc- and Copper-Doped Germanium Infrared-Radiation
Detectors ......................................... . 25
§ 6. Scanning of Infrared Radiation Emitted from InSb Crystals •.••••.•.• 28
§ 7. Other Measurements ....•.............................. 29
Chapter III
Influence of Magnetic Fields on Emission Spectra of p-n Junctions in InAs,
InSb, and PbSe . . . . . . . . . . . . . . . . . • . . . . • . . . . . . . . . .. . . . . . . . . . . . 29
§ 1. Spontaneous and Coherent Radiation Emitted from InAs Injection
Lasers ........................................... . 29
§ 2. Radiation Emitted from InSb Injection Lasers in Strong Magnetic
Fields. Position of Light-Emission Region •••.••.•.•.••••••••• 37
§ 3. Spontaneous and Coherent Radiation Emitted from p-n Junctions
in PbSe. . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . 42
v
vi CONTENTS
Chapter IV
Magnetically Tuned Stimulated Raman Emission from Indium Antimonide ••••.• 47
§ 1. Raman Scattering of Light by Plasmons and Landau Levels in
Semiconductors ... 47
ct ••••••••••••••• 0 ••••••••••••••••••
§ 2. Stimulated Raman Scattering of Light Accompanied by Spin Flip in
Indium Antimonide ...........•..... ~ ..........•...... 51
§ 3, Discussion of Results ................................. . 52
Chapter V
Influence of Pressure on Radiation Emitted from Lead Selenide and
Gallium Arsenide Semiconductor Lasers ••••••••••••••.•••••••••• 55
§ 1. Emission Spectra of PbSe Lasers ••••••.•••.•••.•.•••••.••• 55
§2. Emission Spectra of GaAs Lasers .••••••.•••.•••.•.••.••••• 59
§ 3. Discussion of Results ................................. . 61
Conclusions ............................................ 63
t •
Literature Cited .......................................... . 65
Investigation of the Collective Properties of
Excitons in Germanium by Long-Wavelength
Infrared Spectroscopy Methods
V. A. Zayats
Introduction ••••.• 71
Chapter I
Energy Spectra and Collective Properties of Excitons in Semiconductors •.••• 73
Part 1. Energy Spectrum of Excitons ••••••••.••.••••••••••••••• 73
§ 1. Theoretical Calculations .••••••••••••••.•••.•••••••••••• 73
§ 2. Experimental Results ................................. . 76
Part 2. Collective Properties of Exciton Systems •••••••.•••••.••.•• 77
§ 1. Theoretical Representations •••.•.•.•••.••.••..•..••••.•. 78
§ 2. Discussion of Experimental Results •..•••..•.•.•••••••••••• 80
Chapter II
Methods used in Far-Infrared Investigations of Excitons in
Semiconductors ......................................... . 85
§ 1. Spectroscopic Measurements ..••.••..•••...•....•...••..• 85
§ 2. Apparatus Used in Low-Temperature Optical Measurements under
Interband Excitation Conditions ••••••.•..••••.•••••••••.•• 87
§ 3. Sources of Exciting Radiation ••••••••.••.•.•...•.••..••••• 89
§4. Thermal Conditions .................................. . 91
Chapter III
Far-Infrared Resonance Absorption in Condensed Exciton Phase in
Germanium .••...•..............•..•.•.................. 93
§ 1. Absorption Spectra of Intrinsic Germanium •••••••••••••••••.• 93
§ 2. Discus sion of Parameters of Electron - Hole Drops (no and y) •••••••• 102
§ 3. Temperature Dependence of Resonance Absorption ••••••••••••.• 106
§4. Dependence of Resonance Absorption on Excitation Rate •••••••.••• 108
§ 5. Resonance Absorption in Doped Germanium •••••••.•••••••••.• 111
CONTENTS vii
Chapter IV
Resonance Luminescence of Condensed Exciton Phase in
Germanium ................... 115
0 •••••••••••••••••••••••••
§ 1. Experimental Investigation of Resonance Luminescence •••••.••••• 115
§2. Discussion of Experimental Results. Effective Luminescence
'remperature of Drops ........................................................... .. 119
§ 3. Influence of Inhomogeneous Deformation on Resonance Absorption and
Luminescence. Mobility of Electron-Hole Drops ••••••••••••••• 122
Chapter V
Photoionization and Excitation of Free Excitons in Germanium by
Submillimeter Radiation .......................................... . ' .......................... .. 124
§ 1. Photoionization and Excitation Spectra ••••.•••.•• ••••••• ••••• 124
§ 2. Discussion of Experimental Results. Energy Levels of Excitons ••••• 126
Literature Cited ................................................................................... .. 130
Collective Interactions of Excitons and
Nonequilibrium Carriers in Gallium Arsenide
and Silicon
L. I. Paduchikh
Introduction .................................................................................... .. 133
Chapter I
Collective Interactions of Excitons in Semiconductors 134
Chapter II
Measurement Method ........................................................................... .. 136
§ 1. Optical System and Method of Recording Luminescence
during Continuous Optical Excitation ••.•.•••••••••••••••••• 136
§ 2. Optical System and Method of Recording Luminescence Due to
High-Power Light Pulses ••••••••••.•••••••••••••.••.••• 138
§ 3. Temperature Measurement Method ••••••••.•••.•••••••••..• 139
§ 4. Determination of Temperature Rise in a Semiconductor during
Continuous Optical Excitation •..••••..••.•.••••••••••.••• 139
§ 5. Determination of Temperature Rise in a Semiconductor during
illumination with High-Power Light Pulses •••••••••••••••.••• 142
Chapter TIl
Photoluminescence of Gallium Arsenide ••••••••••.•••••••••••••••. 144
§ 1. Excitons in GaAs and Their Role in Radiative
Recombination .......................................................................... .. 144
§ 2. Investigation of Luminescence Spectra of GaAs at Different Optical
Excitation Rates and Helium Temperatures ••••••••••••••••.•• 145
§ 3. Photoluminescence of GaAs at Temperatures 2-100oK.
Investigation of Temperature Dependence of Recombination
Radiation Intensity ................................................................... .. 149
§ 4. Photoluminescence Spectra of GaAs at T = 77°K •••••••••••..••• 152
§5. Discussion of Results ............................................. . 153
§ 6. Supplement. Possibility of Existence of Condensate in Pure
Epitaxial GaAs Films .......................•......••. 156
viii CONTENTS
Chapter IV
Change in Absorption Coefficient of Undoped GaAs Due to Strong
Optical Excitation .......... 161
l' ••••••••••••••••••••••••••••••
Chapter V
Investigation of Photoluminescence Spectra of Silicon at Different
Optical Excitation Rates ....•....... 164
I; •••••••••••••••••••••••
§ 1. Review of Literature ..................•••.......•..... 164
§ 2. Experimental Investigation of the Photoluminescence of Si at
Different Optical Excitation Rates ••••••••••••••••••••••••• 167
§ 3. Photoluminescence Spectra of Si at Different Temperatures.
Investigation of the Temperature Dependence of the
Luminescence Intensity .............•.•......• 169
0 ••••••••
§4. Determination of the Binding Energy of Free Excitons from the Fall
of the Luminescence Intensity with Rising Temperature •••••••••• 170
§ 5. Discussion of Experimental Results •••••••••••••••••••••.•• 172
Chapter VI
Photoelectric Properties of Silicon at High Optical Excitation Rates •••••••• 174
§ 1. Review of Literature ................................. . 174
§ 2. Measurement Method ...............•.....•............ 174
§ 3 Photoluminescence Spectra of Si in the Presence of Static Electric
0
Fields. Impact Ionization of Free Excitons ••••••••••••••••••• 175
§ 4. Kinetics of Recombination Processes in Si •••••••••••••••••••• 177
§ 5. Investigation of Excitons at High Concentrations in Weak
Electric Fields ....•••...•.•.......... 178
0 ••• fit •••••••••
Literature Cited ••...........••.....................••.... 179
RADIATION EMITTED FROM SEMICONDUCTOR LASERS IN
STRONG MAGNETIC FIELDS AND UNDER HIGH
HYDROSTATIC PRESSURES *
I. I. Zasavi tskii
An investigation was made of the influence of magnetic fields on the emission spectra of lnAs,
lnSb, and PbSe injection lasers and of the influence of pressure on the tuning of the emission
frequency of GaAs and fuSe lasers. Magnetically tunable stimulated Raman emission was ob
tained from n-type lnSb crystals as a result of inelastic scattering of light (A = 10.6 IJl accom
panied by electron-spin flip. The effective masses and g factors of the carriers were determined.
The dependences of the forbidden band width and refractive index on the applied pressure and
magnetic field were obtained.
INTRODUCTION
Investigations of the energy structure of semiconductors are very desirable not only
from the point of view of fundamental knowledge but also because of practical applications.
Very interesting results are obtained when the energy spectrum and, therefore, electrical,
optical, and other properties of a semiconductor are varied by external agencies such as tem
perature, pressure, or magnetic field.
The use of magnetic fields in measurements of the electrical and optical properties has
given the most reliable information on the forbidden-band width, effective mass, and g factor
of carriers, anisotropy of these quantities, and band nonparabolicity of many materials. Strong
magnetic fields change radically the energy spectrum of a crystal because they quantize the
allowed bands into Landau levels or subband s • This makes it possible to study various re
sonance phenomena within a band.
An example of the phenomena that can be studied is the Raman scattering of light by free
carriers localized at Landau levels. The principal parameters of the energy-band structure
can be deduced very accurately from this scattering.
The influence of pressure on a semiconductor is manifested primarily by a change in
the forbidden-band width. However, high pressures also cause other important changes in the
energy structure because they affect not only the absolute extrema, which govern the forbidden
band width, but also the secondary extrema. Therefore, the absolute minimum of the conduc
tion band may shift under pressure. This makes it possible to study higher minima. Moreover,
high pressures may alter significantly the density of states in an allowed band.
*
Thesis submitted for the degree of Candidate of Physicomathematical Sciences, defended
in 1972 at the p. No Lebedev Physic's Institute, Academy of Sciences of the USSR, Moscow.
1
2 I. I. ZASA VITSKII
TABLE 1. Spectral Range of Radiation Emitted by Semicon
ductor Lasers
Excitation
No. Material A, )l l1w, eV method
1 ZnS 0.33 3.8 OE
2 ZnO 0.37 3.4 E
3 Znl_xCdxS 0.32-0.49 3.82-2.5 0
4 ZnSe 0.46 2.7 E
5 CdS 0.49 2.5 OE
6 ZnTe 0.53 2.3 E
7 GaSe 0.59 2.1 E
8 CdSe1_XSX 0.49-0.68 2.5-1.8 OE
9 CdSe 0.675 1.8 OE
10 Ai1_XGa",As 0.63-0.90 2.0-1.4 I
11 GaAs1_XPX 0.61-0.90 2.U-1.4 EI
12 CdTe 0.785 1.6 E
13 GaAs 0.83-0.91 1.50-1.36 o EI A
14 InP 0.91 1.36 I A
1.5 GaAs1_XSbx 0.9-1.5 1.4-0.83 I
16 CdSnP2 1.01 1.25 E
17 InAs1_XPX 0.9-3.2 1.4-0.39 I
18 GaSh 1.55 0.80 EI
19 Inl_XGaxAs 0.85-3.1 1.45-0.40 I
2210 CIndAaPs 2 32..11 00..6598 o0 E I
22 InA~l_xShx 3.1-5.4 0.39-0.23 I
23 Cd1_xHgxTe 3-15 0.41-0.08 OE
24 Te 3.72 0.334 E
25 PbS 4.3 0.29 o E I
26 InSb 5.2 0.236 o E I A
27 PbTe 6.5 0.19 o E I
28 PbS1_XSe 3.9-8.5 0.32-0.146 o E I
29 PbSe X 8.5 0.146 E I
30 Pb1_XSnxTe 6-28 0.209-0045 o E I
31 Pb1_XSnXSe 8-31.2 0.155-0.U40 I
Note. The notation used in the fifth column is as follows: 0 is optical pumping, E is
electron-beam pumping, I is carrier injection, A is avalanche breakdown.
In view of these radical changes in the energy structure of a crystal under the influence
of a magnetic field or pressure, we can naturally expect a strong dependence of the charac
teristics of the radiation emitted by a crystal on the applied magnetic field or pressure.
With these points in mind it would be interesting to study the dependence of the emission
frequency of semiconductor lasers on the applied pressure and magnetic field because this
would give information on the energy spectrum and also help in designing high-power tunable
sources of monochromatic radiation. We shall now consider in greater detail the problem of
tunability of coherent radiation frequency.
Currently available lasers can emit radiation of wavelengths ranging from near ultra
violet to far infrared. The active media used in lasers are solids, including semiconductors
[1-7], liquids, and gases,
Table 1 gives the published information (see, for example, [8)) on the characteristics
of currently available lasers. An examination of this table shows that semiconductor lasers
emit over a wide spectral range. For example, zinc sulfide excited by electron bombardment
emits coherent radiation at A. == 0.33 J1. [9), whereas the Pb1_xSnxSe (x == 0.19) injection laser
emits radiation with A. ~ 31 J1. and can be tuned by a magnetic field up to 34 11 [10).
There are several ways of ensuring tunability of the coherent radiation frequency.
The first method is to increase the range of available frequencies by a suitable selection
of new active media and by utilization of all possible transitions in the emission spectra of
these media. The number of semiconducting materials which can emit coherent radiation is
about thirty. However, this number is found to be much larger if we include also lasers made
of solid -solutions of some semiconductor compounds (ZnCdS, CdSeS, AIGaAs, GaAsP, GaAsSb, InAsP,