Working Group Silicon & Germanium Nanocrystals - Summary

The guiding idea of our research is the preparation and characterization of crystalline micro- and nanostructures – primarily for cost and material saving applications in the field of energy conversion and storage.
Concerning low-cost silicon solar cells, the activities are focused on the growth of microcrystalline silicon layers on amorphous substrates. A specific process, which allows the controlled preparation of seed layers has been developed. Induced by metallic droplets, an amorphous silicon layer deposited by physical vapor deposition is converted into a layer of contiguous microcrystals by an amorphous-liquid-crystalline (ALC) phase transition. Subsequent crystallization of silicon onto the ALC seed layer from a metallic solution is achieved at glass compatible temperatures by the temperature difference method (TDM) – a process that has been developed by this team as well. The optimization of this process is supported by numerical modeling of heat and mass transport phenomena using the software CFX. The characterization of structural, optical and electrical properties of the microcrystalline absorber material for solar cells is actually carried out with high priority.

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Another research field of the group is the preparation of isolated Cu(InxGa1 x)Se2 (CIGSe) islands as absorbers for micro-concentrator solar cells. One substantial advantage using such microstructures compared to continuous layers is the saving of rare elements such as indium. Simultaneously, the micro absorbers allow to enhance the energy conversion and thus to increase the efficiency factor.

The third research topic of the group deals with the selective control of growth directions and morphology of Si/Ge nanowires. Nanowires of different Si/Ge composition are obtained using the VLS method. In this process, liquid gold droplets on the substrate surface act as growth catalysts and define the geometry of the nanowires. Such functional components can potentially be applied to thermoelectric generators. Due to their specific morphology, a very high efficiency of thermoelectric energy conversion is expected.

Key Publications

R. Bansen, R. Heimburger, J. Schmidtbauer, T. Teubner, T. Markurt, C. Ehlers, T. Boeck
Crystalline Silicon on Glass by Steady-State Solution Growth Using Indium as Solvent.
APPL PHYS A 119 (2015) 1577 - 1586
doi:10.1007/s00339-015-9141-0

F. Ringleb, K. Eylers, T. Teubner, T. Boeck, C. Symietz, J. Bonse, S. Andree, J. Krüger, B.
Heidmann, M. Schmid, M. Lux-Steiner
Regularly Arranged Indium Islands on Glass/Molybdenum Substrates upon Femtosecond Laser and Physical Vapor Deposition Processing.
APPL PHYS LETT 108 (2016) 111904
doi: 10.1063/1.4943794

J. Schmidtbauer, R. Bansen, R. Heimburger, Th. Teubner, T. Boeck
MBE Growth of Germanium Nanowires Along 〈110〉.
J CRYST GROWTH 406 (2014) 36 - 40.
doi:10.1016/j.jcrysgro.2014.08.013

 

Working Group Silicon & Germanium Nanocrystals - Methods

Deposition methods:

  • Physical Vapor Deposition (PVD) of Mo, Si, Sn, Cu, In, Ga
  • Molecular Beam Epitaxy for Si/Ge growth using both solid sources (MBE) and gaseous precursors (GSMBE)
  • Liquid Phase Epitaxy (LPE) at stationary temperature gradients (TDM) for Si growth using Sn as solvent
  • Conventional Liquid Phase Epitaxy (LPE) for Si/Ge growth using In, Sn, or Bi as solvents

Special variations of crystallization from solution

  • Recrystallization of amorphous layers by metallic droplets acting as solvent (ALC)
  • Preparation of spatially confined metallic Cu-In micro-islands as precursors for the conversion to chalcopyrite microstructures.
  • Growth of Si/Ge nanostructures by the vapor-liquid-solid (VLS) method
  • Numerical modelling of heat and mass transport phenomena using the software CFX
  • Morphological characterization using scanning electron microscopy (SEM) and scanning force microscopy (SFM)
  • Spatially resolved chemical characterization by energy-dispersive X-ray spectroscopy (EDX)
  • Crystallographic in situ characterization by reflection high-energy electron diffraction (RHEED)

Working Group Silicon & Germanium Nanocrystals - Publications

Publications

F. Ringleb, K. Eylers, Th. Teubner, H.-P. Schramm, C. Symietz, J. Bonse, S. Andree, B. Heidmann, M. Schmid , J. Krüger, T. Boeck
Growth and shape of indium islands on molybdenum atmicro-roughened spots created by femtosecond laser pulses
APPL SURF SCI 418 (2017) 548 – 553
doi:10.1016/j.apsusc.2016.11.135

C. Ehlers, R. Bansen, T. Markurt, D. Uebel, Th. Teubner, T. Boeck
Solution growth of Si on reorganized porous Si foils and on glass substrates
J CRYST GROWTH 468 (2017) 268 – 271
doi:10.1016/j.jcrysgro.2016.12.040

T. Boeck, F. Ringleb, R. Bansen
Growth of crystalline semiconductor structures on amorphous substrates for photovoltaic applications
Cryst. Res. Technol. 52, No. 1 (2017) 1600239
doi: 10.1002/crat.201600239

R. Bansen, C. Ehlers, Th. Teubner, T. Boeck
Steady-State Solution Growth of Microcrystalline Silicon on Nanocrystalline Seed Layers on Glass
J SEMICONDUCTORS 37 (2016) 093001
doi: 10.1088/1674-4926/37/9/093001

R. Bansen, C. Ehlers, Th. Teubner, K. Boettcher, K. Gambaryan, J. Schmidtbauer, T. Boeck
Silicon on Glass Grown from Indium and Tin Solutions
J PHOTON ENERGY 6 (2016) 025501    
doi: 10.1117/1.JPE.6.025501

S. Dadgostar, J. Schmidtbauer, T. Boeck, A. Torres, O. Martínez, J. Jiménez, J. W. Tomm, A. Mogilatenko, W. T. Masselink, F. Hatami
GaAs/GaP Quantum Dots: Ensemble of Direct and Indirect Heterostructures with Room Temperature Optical Emission
APPL PHYS LETT 108 (2016) 102103
doi: 10.1063/1.4943503

R. Bansen, C. Ehlers, Th. Teubner, T. Markurt, J. Schmidtbauer, T. Boeck
Continuous Polycrystalline Silicon Layers on Glass Grown from Tin Solutions
CRYST ENG COMM 18 (2016) 1911 - 1917        
doi: 10.1039/c5ce02530c

B. K. Tanner, J. Garagorri, E. Gorostegui-Colinas, M. R. Elizalde, D. Allen, P. J. McNally, J. Wittge, C. Ehlers and A. N. Danilewsky
X-Ray Asterism and the Structure of Cracks from Indentations in Silicon
J APPL CRYST 49 (2016) 250 - 259    
doi: 10.1107/S1600576715024620

V.G. Dubrovskii, Y. Berdnikov, J. Schmidtbauer, M. Borg, K. Storm, K. Deppert, J. Johansson
Length Distributions of Nanowires Growing by Surface Diffusion
CRYST GROWTH DES 16 (2016) 2167 - 2172            
doi: 10.1021/acs.cgd.5b01832

F. Ringleb, K. Eylers, T. Teubner, T. Boeck, C. Symietz, J. Bonse, S. Andree, J. Krüger, B. Heidmann, M. Schmid, M. Lux-Steiner
Regularly Arranged Indium Islands on Glass/Molybdenum Substrates upon Femtosecond Laser and Physical Vapor Deposition Processing.
APPL PHYS LETT 108 (2016) 111904
doi: 10.1063/1.4943794

B. Süss, F. Ringleb, J. Heberle
New Ultrarapid-Scanning Interferometer for FT-IR Spectroscopy with Microsecond Time-Resolution
REV SCI INSTRUM 87 (2016) 063113
doi: 10.1063/1.4953658

R. Bansen, R. Heimburger, J. Schmidtbauer, T. Teubner, T. Markurt, C. Ehlers, T. Boeck
Crystalline Silicon on Glass by Steady-State Solution Growth Using Indium as Solvent.
APPL PHYS A 119 (2015) 1577 - 1586
doi:10.1007/s00339-015-9141-0

S. Dadgostar, E. H. Hussein, J. Schmidtbauer, T. Boeck, F. Hatami, W. T. Masselink
Structural Properties of AlGaP Films on GaP Grown by Gas-Source Molecular-Beam Epitaxy.
J CRYST GROWTH 425 (2015) 94 - 98
doi: 10.1016/j.jcrysgro.2015.03.015

J. Schmidtbauer, R. Bansen, R. Heimburger, Th. Teubner, T. Boeck
MBE Growth of Germanium Nanowires Along 〈110〉.
J CRYST GROWTH 406 (2014) 36 – 40.
doi:10.1016/j.jcrysgro.2014.08.013

R. Bansen, J. Schmidtbauer, U. Juda, T. Markurt, Th. Teubner, R. Heimburger, T. Boeck
Influence of Surface Roughness on Ge Nanowire Growth by MBE. 
Physica Status Solidi (RRL) - Rapid Research Letters, 7(10) (2013) 831–834.
doi:10.1002/pssr.201307248

Bansen, J. Schmidtbauer, R. Gurke, Th. Teubner, R. Heimburger, T. Boeck
Ge In-Plane Nanowires Grown by MBE: Influence of Surface Treatment.
CrystEngComm 15 (2013) 3478 – 3483.
doi:10.1039/C3CE27047E

Teubner, R. Heimburger, T. Boeck, R. Fornari
Growth Kinetics on Silicon Facets During Low-Temperature Crystallization from Indium Solution.
Journal of Crystal Growth 347 (2012) 31 – 36.
doi:10.1016/j.jcrysgro.2012.03.004

Heimburger, R. Bansen, T. Markurt, J. Schmidtbauer, Th. Teubner, T. Boeck
Solvent-Induced Growth of Crystalline Silicon on Glass. 
In 2012 38th IEEE Photovoltaic Specialists Conference, Austin (2012) 000333–000337.
doi:10.1109/PVSC.2012.6317630

Heimburger, N. Deßmann, T. Teubner, H.-P. Schramm, T. Boeck, R. Fornari
Polycrystalline Silicon Films on Glass Grown by Amorphous-Liquid-Crystalline Transition at Temperatures Below 330°C.
Thin Solid Films 520 (2012) 1784 – 1788.
doi:10.1016/j.tsf.2011.08.084

Heimburger, Th. Teubner, N. Deßmann, H.-P. Schramm, T. Boeck, R. Fornari 
Solution Growth of Crystalline Silicon on Glass in the In–Si–Mo System.
Journal of Crystal Growth 312 (2010) 1632 – 1635.
doi:10.1016/j.jcrysgro.2010.01.043

Th. Teubner, R. Heimburger, K. Böttcher, T. Boeck, R. Fornari 
Equipment for Low-TemperatureSteady State Growth of Silicon from Metallic Solutions.
Crystal Growth & Design 8 (2008) 2484 – 2488.
doi:10.1021/cg800120q

Patente

T. Boeck,  R. Fornari, R. Heimburger, G. Schadow, J. Schmidtbauer, H.-P. Schramm, T. Teubner
Kristallisationsverfahren zur Erzeugung kristalliner Halbleiterschichten.
Deutsches Patent und Markenamt 2012-05-16
DE 102010044014 A1

T. Boeck, A. Braun, K. Schmidt
Verfahren zur Herstellung von kristallinen Schichten.
Deutsches Patent- und Markenamt 2001-06-27
EP 0843748 B1

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