Electro-optical properties of dislocations in silicon and their possible application for light emitters [Elektronische Ressource] / vorgelegt von Tzanimir Vladimirov Arguirov

Tzanimir

Sujets

• Physik

Informations

• Publié par: brandenburgische_technische_universitat_cottbus
• Publié le: 01 janvier 2007
• Nombre de lectures: 24
• Langue: English
• Poids de l'ouvrage: 3 Mo

Extrait

Electro-optical properties of dislocations in silicon and
their possible application for light emitters





Von der Fakultät für Mathematik, Naturwissenschaften und Informatik
der Brandenburgischen Technischen Universität Cottbus







zur Erlangung des akademischen Grades
Doktor der Naturwissenschaften
(Dr. rer. nat.)

genehmigte
Dissertation
vorgelegt von




Diplom-Ingenieurphysiker

Tzanimir Vladimirov Arguirov
geboren am 12. Mai 1971 in Sofia, Bulgarien


Gutachter:
Prof. Dr. rer. nat. habil Jürgen Reif
Prof. Dr. sc. nat. Martin Kittler
Prof. Dr. rer. nat. habil Hans-Joachim Fitting







Tag der mündlichen Prüfung: 14.10.2007 2
Contents


Introduction _______________________________________________________________ 5
Aim and outline of the work___________________________________________________ 6
Part I _____________________________________________________________________ 8
RECOMBINATION PROCESSES IN SILICON
Chapter 1__________________________________________________________________ 9
Recombination processes in silicon with dislocations
1.1. Radiative recombination. Bimolecular and monomolecular rate equations. ________ 9
1.2. Nonradiative recombination in silicon ______________________________________ 13
1.3. Dislocation recombination activity_________________________________________ 15
1.4. Temperature dependence of dislocation-related luminescence __________________ 22
1.5. Summary______________________________________________________________ 25
Chapter 2_________________________________________________________________ 26
Dislocation-related radiation
2.1. Origin of the dislocation luminescence______________________________________ 27
2.2. Relation between the dislocation lines 33
2.3. Dislocation luminescence on non-relaxed dislocations _________________________ 36
2.4. Summary 36
Chapter 3 37
Experimental methods and investigated materials
3.1. Luminescence in silicon __________________________________________________ 37
3.2. “Spectral Response” Technique ___________________________________________ 45
3.3. Electron beam induced current mapping ___________________________________ 46
3.4. Materials and treatment of the multicrystalline samples_______________________ 46
3.5. for silicon based light emitters 48
3.6. Summary______________________________________________________________ 49
Part II ___________________________________________________________________ 50
Characterisation of solar cell grade silicon by means of scanning photoluminescence
spectroscopy 50
Chapter 4_________________________________________________________________ 51
Correlation between electrical and optical activities in EFG silicon. Influence of the
surface recombination and stress.
4.1. Correlation between the electrical and the radiative activity of the
dislocations in EFG silicon ______________________________________________________ 52
4.2. Temperature behaviour of the luminescence ________________________________ 57
4.3. Role of gettering ________________________________________________________ 65 3
4.4. Relation between D3 and D4 spatial distribution of intensities __________________ 69
4.5. Summary______________________________________________________________ 73
Chapter 5_________________________________________________________________ 75
Radiative defects in block cast and HEM silicon
5.1. Gettering zone around grain boundaries____________________________________ 75
5.2. βFeSi precipitates ______________________________________________________ 76 2
5.3. Very intense, D3-like emission ____________________________________________ 81
5.4. Summary 85
Part III __________________________________________________________________ 86
Silicon based light emitters
Chapter 6_________________________________________________________________ 87
Light emitting diodes based on silicon - different approaches
6.1. Engineered silicon structures _____________________________________________ 88
6.2. LEDs based on radiation induced by foreign species __________________________ 91
6.3. Band-to-band radiation enhancement ______________________________________ 93
6.4. Summary______________________________________________________________ 94
Chapter 7 96
Discussion of the parameters
7.1. Internal, external and power efficiency _____________________________________ 96
7.2. Light escape cone, Lambertian emission pattern, extraction coefficient __________ 97
7.3. Calibration for absolute measurements of the radiant flux ____________________ 100
7.4. Summary_____________________________________________________________ 101
Chapter 8________________________________________________________________ 102
Band-to-band light emitters prepared by implantation and annealing
8.1. Model describing the efficiency __________________________________________ 104
8.2. Sample preparation ____________________________________________________ 106
8.3. Formation of extended defects ___________________________________________ 107
8.4. Correlation of the room temperature electroluminescence with the e
xtended defects concentration __________________________________________________ 108
8.5. Correlation of the luminescence efficiency with annealing and implantation
parameters __________________________________________________________________ 110
8.6. Anomalous temperature dependence of the luminescence_____________________ 112
8.7. Role of the dopant profile in the diode emitter ______________________________ 115
8.8. Gettering effect during the annealing step__________________________________ 116
8.9. Internal quantum efficiency dependence on the injection 117
8.10. Sample thinning and disappearance of the luminescence _____________________ 118
8.11. Summary_____________________________________________________________ 121
Chapter 9________________________________________________________________ 122 4
Light emitters based on dislocation-related radiation
9.1. Radiation from implantation induced extended defects_______________________ 123
9.2. Dislocation radiation from SiGe buffer layers ______________________________ 127
9.3. Light emission from dislocation networks prepared by direct wafer bonding ____ 129
9.4. Concepts for electrical excitation of the dislocation network __________________ 136
9.5. Summary_____________________________________________________________ 140
Conclusions 142
References_______________________________________________________________ 144
List of abbreviation and symbols _____________________________________________ 152
Acknowledgements ________________________________________________________ 154
5
Introduction

Dislocations in silicon can have a decisive influence on the performance of electronic devices.
The interest in the dislocation properties is driven mainly because of two practical reasons. One
is the application of multicrystalline silicon for solar cells production, which contains
dislocations [Möl1996, Sch2004], and the other is the possibility to enhance the raditive
properties of the silicon by introducing dislocations [Ng2001, Pan2004, Pav2003, Kve2005]. A
deeper understanding is required of the mechanisms governing the dislocation recombination
activity, their radiation, and how they interact with other defects present in silicon.
The dislocation specific radiation may provide a means for optical diagnostics of solar cell
grade silicon.
One broad application of the solar energy requires decreasing of the production costs while
increasing the efficiency of the solar cells. Multicrystalline silicon is an alternative, which
meets both the low cost production and the high efficiency requirements for solar cells. The
production of highly efficient solar cells require high minority carrier lifetime in the starting
material and effective lifetime updating during the processing into solar cell. It is recognized
that a high dislocation density is one of the major factors which limits the material quality and
their recombination activity is decisive for the carrier lifetime and diffusion length [Möl1996].
A technique which gives spectroscopic access to the dislocation activity is the investigation
of the photoluminescence [Mudr2002, Ost1999, Kos1999, Tar1999]. Since multicristalline
silicon wafers are inhomogeneous, there is a need to combine the spectral capabilities with the
ability of spatially resolving the defect areas [Ost2000, Tar2000].
Enhancement of band-to-band radiation or strong dislocation-related radiation may provide a
means for on-chip optical data transfer. Due to complexity of the current ultra large integrated
circuits and meanwhile very fast switching times of the single transistors, a situation is
reached where the signal delay is limited by transfer in the interconnects. It is reasonable to
expect that the integration is progressing such that the length of the wiring on a single chip
will be getting longer and longer. The total length of the interconnects of a modern
microprocessor is estimated to several kilometres, and follow