Device physics of narrow gap semiconductors

521 Pages·2010·12.22 MB·English

by  Junhao Chu

Microdevices: Physics and Fabrication Technologies
SeriesEditors
ArdenSher
SRIInternational
MenloPark,CA
USA
MarcyA.Berding
AppliedOpticsLaboratory
SRIInternational
MenloPark,CA
USA
Forothertitlespublishedinthisseries,goto
http://www.springer.com/series/6269
Junhao Chu (cid:129) Arden Sher
Device Physics of Narrow
Gap Semiconductors
123
JunhaoChu ArdenSher
NationalLaboratoryforInfraredPhysics SRIInternational(Retired)
ShanghaiInstituteofTechnicalPhysics,CAS 333RavenswoodAve.
Shanghai200083,China MenloPark
[email protected] CA94025-3493,USA
[email protected]
and
LaboratoryofPolarMaterialsandDevices
EastChinaNormalUniversity
Shanghai200241
[email protected]
ISBN978-1-4419-1039-4 e-ISBN978-1-4419-1040-0
DOI10.1007/978-1-4419-1040-0
SpringerNewYorkDordrechtHeidelbergLondon
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(cid:2)c SpringerScience+BusinessMedia,LLC2010
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Foreword
Thesubjectofsemiconductorscienceandtechnologygainedimportanceinthelatter
halfofthetwentiethcenturywiththefirststagesstudiesofresearchongroupIVele-
mentsandIII–Vgroupbinarycompoundsemiconductors.Muchoftheearlydevice
workconcentratedonPbSnTealloys,butthismaterialhadseveralproblemsrelated
toitshigh-dielectricconstant.TheIII–Vcompoundsemiconductorwiththenarrow-
estgapwasInSb(energygapis0.18eVatroomtemperature)andwasnotsuitedto
themid-waveorlong-waveinfraredranges.Tosatisfythedemandoftheinfraredde-
tectiontechnology,anarrowgapsemiconductoralloyappearedin1959,theternary
alloy Hg Cd Te based on HgTe and CdTe, from which narrower bandgaps can
1(cid:2)x x
be reached. By changing the composition value of x, it was possible to meet the
demands of infrared detectors in several important wave bands. Meanwhile, some
interestingphysicalpropertiesappearedduetothenarrowerenergybandgap.Itim-
mediatelyattractedintensiveresearchattention.Professionaldiscussionsrelatedto
this material appeared around 1976. In 1976, an international conference named
“Narrow Gap Semiconductors” was initiated. From then on, several other confer-
encesrelatedto“II–VIGroupSemiconductors”or“NarrowGapSemiconductors”
havebeenheld,forexample,theconferencessponsoredbyNATO.Thescaleofev-
eryconferencewaslargesothattheirproceedingsformedthebasisofanimportant
branchofsemiconductorscience.Duringthisrapiddevelopmentalprocess,several
proceedingsandreviewpapersrelatedtothistypeofsemiconductorwerepublished.
Tomyknowledge,thisbookisthefirstinternationaltreatisewhichfullyreviewsthe
researchresultsofnarrowgapsemiconductors.
One of the authors of this book, Professor Junhao Chu, has made many contri-
butionstothefieldofnarrowgapsemiconductors.Heisconsideredoneofthemost
suitable authors for a comprehensive book on narrow gap semiconductor physics.
He was invited to update the database of Hg-based semiconductors for the new
versions of “Landolt-Bornstein: Numerical Data and Functional Relationships in
ScienceandTechnology”publishedin1999and2008.
It has been my pleasure to read this book and the authors’ previous book
(“Physics and Properties of Narrow Gap Semiconductors,” Springer 2008) in de-
tail.TheyexploremanyresearchfieldsofHgCdTe,includingbasiccrystallographic
propertiesandgrowthmethodsfromearlystudiestopresentresearch,principlesand
measurementsofphysicalphenomena,andsoon.Therefore,thisbookisnotonlya
v
vi Foreword
necessaryreferenceforthosewhoundertakeresearch,teaching,andindustrialwork
onnarrowgapmaterials,butalsoofvalueforthoseundertakingworkrelatedtoall
semiconductors.
Prof.Ding-YuanTang
MemberofChineseAcademyofSciences
ShanghaiInstituteofTechnicalPhysics,CAS
Preface
Thephysicsofnarrowgapsemiconductorsisanimportantbranchofsemiconductor
science.Researchintothisbranchfocusesonaspecificclassofsemiconductorma-
terialswhichhavenarrowforbiddenbandgaps.Paststudiesonthisspecificclassof
semiconductor materials have revealed not only general physical principles appli-
cable to all semiconductors, but also those unique characteristics originating from
the narrow band gaps, and therefore have significantly contributed to science and
technology. Historically, developments of narrow gap semiconductor physics have
been closely related to the development of the science and technology of infrared
opticalelectronicsinwhichnarrowgapsemiconductorshaveplayedavitalrolein
detectorsandemitters,andotherhighspeeddevices.Thisbookisdedicatedtothe
study of narrow gap semiconductors and their applications. It is expected that the
present volume will be valuable not only in the understanding of the fundamental
scienceofthesematerialsbutalsothetechnologyofinfraredopticalelectronics.
Therehavebeenseveralbookspublishedinthisfieldinrecentdecades.In1977,a
Britishscientist,D.R.Lovett,published“SemimetalsandNarrow-BandGapSemi-
conductors” (Pion Limited, London). Later, German scientists R. Dornhaus and
G. Nimtz published a comprehensive review article in 1978, whose second edi-
tion, “The Properties and Applications of the HgCdTe Alloy System, in Narrow
GapSemiconductors,”wasreprintedbySpringerin1983(SpringerTractsinMod-
ernPhysics,Vol.98,p.119).Thesetwodocumentsincludedsystematicdiscussions
ofthephysicalpropertiesofnarrow-gapsemiconductorsandarestillimportantref-
erences in the field. In 1980, the 18th volume of the series “Semiconductors and
Semimetals” (edited by R.K.Willardson and Albert C. Beer) in which very use-
ful reviews were collected, was dedicated to HgCdTe semiconductor alloys and
devices. In 1991, a Chinese scientist, Prof. D. Y. Tang, published an important ar-
ticle, “Infrared Detectors of Narrow Gap Semiconductors,” in the book “Research
andProgressofSemiconductorDevices”(editedbyS.W.Wang,SciencePublish-
ers,Beijing,p.1–107),inwhichthefundamentalprinciplesdrivingHgCdTe-based
infrared radiation detector technology were comprehensively discussed. In addi-
tion,ahandbook,“PropertiesofNarrowGapCadmium-basedCompounds”(edited
by P. Capper), was published in the United Kingdom in 1994. This handbook
vii
viii Preface
contains a number of research articles about the physical and chemical properties
of HgCdTe narrow-gap semiconductors and presents various data and references
aboutCd-basedsemiconductors.
This book, “Device Physics of Narrow Gap Semiconductors,” is the second in
atwo–volumesequenceonnarrowgapsemiconductors.Thefirstvolume,“Physics
and Properties of Narrow Gap Semiconductors,” (Springer 2008), focuses mainly
on materials physics and fundamental properties. Both volumes describe a variety
of narrow gap semiconductor materials and revealing the intrinsic physical prin-
ciples that govern their behavior. In this book, narrow gap semiconductors are
presented within the larger framework of semiconductor physics. In particular, a
unique property of this book is its extensive collection of results of research de-
duced by Chinese scientists, including one of the authors of this book, although
the results are integrated into the larger body of knowledge on narrow gap semi-
conductormaterialsanddevices.Inorganizingthebook,specialattentionwaspaid
tobridgingthegapbetweenbasicphysicalprinciplesandfrontierresearch.Thisis
achievedthroughextensivediscussionsofvariousaspectsofthefrontiertheoretical
and experimental scientific issues and by connecting them to device-related tech-
nology.Itisexpectedthatbothstudentsandresearchersworkinginrelevantfields
willbenefitfromthisbook.
The effort was encouraged by Prof. D. Y. Tang. J. Chu is most grateful to
Prof. D. Y. Tang’s critical reading of the manuscript and invaluable suggestions
and comments. A. Sher is indebted to Prof. A-B Chen for invaluable suggestions.
The authors are also grateful to numerous students and colleagues who over the
yearshaveofferedvaluablesupportduringthewritingofthisbook.TheyareDrs:
Y. Chang, K. Liu, Y. S. Gui, X. C. Zhang, J. Shao, L. Chu, Y. Cai, B. Li, Z. M.
Huang, X. Lu¨, L. He, M. A. Berding, and S. Krishnamurthy. We are indebted to
ProfessorM.W.Mu¨llerforhiscarefulreadingoftheEnglishmanuscriptofVol.I.
TheelectronicfilesofthemanuscriptswereeditedbyDr.H.ShenandDr.X.Lu¨.
TheresearchofJ.Chu’sgroupasispresentedinthisbookwassupportedbythe
National Natural Science Foundation of China, the Ministry of Science and Tech-
nologyofthePeople’sRepublicofChina,theChineseAcademyofScience,andthe
ScienceandTechnologyCommissionoftheShanghaiMunicipality.
March2009 JunhaoChu
ArdenSher
Contents
1 Introduction.................................................................... 1
2 ImpuritiesandDefects........................................................ 5
2.1 ConductivityandIonizationEnergiesofImpurities
andNativePointDefects............................................. 5
2.1.1 Defects........................................................ 5
2.1.2 Chemical Analysis of Impurity Defects
andtheirConductivityModifications ....................... 10
2.1.3 TheoreticalEstimationMethodforImpurityLevels ....... 14
2.1.4 DopingBehavior............................................. 27
2.1.5 ExperimentalMethods....................................... 34
2.2 ShallowImpurities ................................................... 46
2.2.1 Introduction................................................... 46
2.2.2 ShallowDonorImpurities ................................... 49
2.2.3 ShallowAcceptorImpurities ................................ 54
2.3 DeepLevels........................................................... 61
2.3.1 DeepLevelTransientSpectroscopyofHgCdTe............ 61
2.3.2 DeepLevelAdmittanceSpectroscopyofHgCdTe ......... 69
2.3.3 FrequencySweptConductanceSpectroscopy .............. 75
2.4 ResonantDefectStates............................................... 79
2.4.1 CapacitanceSpectroscopyofResonantDefectStates...... 80
2.4.2 TheoreticalModel............................................ 83
2.4.3 ResonantStatesofCationSubstitutionalImpurities ....... 85
2.5 PhotoluminescenceSpectroscopyofImpuritiesandDefects....... 87
2.5.1 Introduction................................................... 87
2.5.2 TheoreticalBackgroundforPhotoluminescence ........... 89
2.5.3 InfraredPLfromanSb-DopedHgCdTe....................103
2.5.4 InfraredPLinAs-dopedHgCdTeEpilayers................108
2.5.5 BehaviorofFeasanImpurityinHgCdTe..................113
References.......................................................................119
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