Transmission electron microscopy of GaN based, doped semiconductor heterostructures [Elektronische Ressource] / von Angelika Pretorius

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• Physik

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• Publié par: universitat_bremen
• Publié le: 01 janvier 2006
• Nombre de lectures: 124
• Poids de l'ouvrage: 28 Mo

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Transmission electron microscopy
of GaN based, doped
semiconductor heterostructures
Angelika Pretorius
Universit¨at Bremen 2006Transmission electron microscopy
of GaN based, doped
semiconductor heterostructures
Vom Fachbereich fu¨r Physik und Elektrotechnik
der Universit¨at Bremen
zur Erlangung des akademischen Grades eines
Doktor der Naturwissenschaften (Dr. rer. nat.)
genehmigte Dissertation
von
Dipl. Phys. Angelika Pretorius
aus Dorsten
1. Gutachter Prof. Dr. rer. nat. A. Rosenauer
2. Gutachter Prof. Dr. rer. nat. D. Hommel
Eingereicht am: 26.07.2006
Tag des Promotionskolloquiums: 09.10.2006Contents
Abbreviations v
1 Introduction 1
2 Basics 5
2.1 The material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1.1 Crystal structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1.2 In Ga N phase diagram . . . . . . . . . . . . . . . . . . . . . . . 8x 1−x
2.1.3 Doping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.1.4 Optical properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.2 Epitaxial growth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.2.1 Metalorganic vapour phase epitaxy . . . . . . . . . . . . . . . . . . 14
2.2.2 Molecular beam epitaxy . . . . . . . . . . . . . . . . . . . . . . . . 15
2.3 Growth modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3 TEM theory and evaluation 19
3.1 Electron diffraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
3.1.1 Kinematic theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
3.1.2 Dynamic theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
3.2 Image formation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
3.2.1 Effect of incoherence . . . . . . . . . . . . . . . . . . . . . . . . . . 33
3.3 Evaluation of In concentration in In Ga N structures . . . . . . . . . . . 35x 1−x
3.3.1 Derivation of lattice distances . . . . . . . . . . . . . . . . . . . . . 36
3.3.2 Strain state analysis . . . . . . . . . . . . . . . . . . . . . . . . . . 39
iii Contents
3.3.3 Sources of error in derivation of the In concentration x . . . . . . . 42
3.4 Polarity measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
4 Pyramidal defects in Mg doped GaN 59
4.1 Experimental . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
4.2 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
4.3 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
5 In Ga N islands 71x 1−x
5.1 Literature survey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
5.1.1 Patterning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
5.1.2 Antisurfactants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
5.1.3 Stranski-Krastanow growth mode . . . . . . . . . . . . . . . . . . . 74
5.1.4 Growth interruptions . . . . . . . . . . . . . . . . . . . . . . . . . . 75
5.1.5 Droplet epitaxy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
5.1.6 Fluctuation of QW width . . . . . . . . . . . . . . . . . . . . . . . 77
5.1.7 Phase separation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
5.1.8 Segregation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
5.1.9 Other effects concerning island formation . . . . . . . . . . . . . . . 81
5.2 Recognition of In droplets . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
5.3 MBE grown In Ga N islands . . . . . . . . . . . . . . . . . . . . . . . . 85x 1−x
5.3.1 Low temperature growth of In Ga N island samples . . . . . . . 86x 1−x
5.3.2 High temperature growth of In Ga N island samples . . . . . . . 96x 1−x
5.4 MOVPE grown In Ga N islands . . . . . . . . . . . . . . . . . . . . . . 103x 1−x
5.4.1 Geometric In Ga N islands . . . . . . . . . . . . . . . . . . . . . 103x 1−x
5.4.2 In Ga N sample series with QD like PL . . . . . . . . . . . . . . 118x 1−x
5.5 Concentration profile of geometric In Ga N islands grown by MOVPE . 124x 1−x
6 Summary and outlook 133Contents iii
A General notes 137
A.1 Physical constants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137
A.2 Vacuum classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137
A.3 Brackets for directions, planes, and reflections . . . . . . . . . . . . . . . . 138
A.4 Special planes in crystals of hexagonal structure . . . . . . . . . . . . . . . 139
A.5 Centre of Laue circle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
B Fourier transform, δ-function, and convolution 141
C Fit functions 143
D List of island samples 145Abbreviations
AFM atomic force microscopy
BF bright field
CBED convergent beam electron diffraction
CCD charge coupled device
CD compact disc
COLC centre of Laue circle
CTF coherent transfer function
DALI digital analysis of lattice images
DFT density functional theory
DP diffraction pattern
DVD digital video disc
EDS energy dispersive x-ray spectroscopy
EELS electron energy loss spectroscopy
EMS electron microscopy image simulation
fcc face centred cubic
FE finite element
FEG field emission gun
FIB focused ion beam
FOLZ first order Laue zonevi Abbreviations
FVIR focus variation image reconstruction
FWHM full width at half maximum
HAADF high angle annular dark field
HOLZ higher order Laue zone
HRTEM high resolution transmission electron microscopy
ID inversion domain
IDB inversion domain boundary
laser light amplification by stimulated emission of radiation
LD laser diode
LED light emitting diode
LEEBI low energy electron beam irradiation
MAL maximum likelihood
MBE molecular beam epitaxy
ML monolayer
MOVPE metalorganic vapour phase epitaxy
MQW multiple quantum well
PD pyramidal defect
PL photo luminescence
QD quantum dot
QW quantum well
relrod reciprocal lattice rod
RHEED reflection high energy electron diffraction
RT room temperature
SAD selected area diffraction
sccm standard cubic centimeter per minute