Lateral Ordering of Self-Assembled Ge Islands

1998 ◽  
Vol 533 ◽  
Author(s):  
Jian-Hong Zhu ◽  
K. Brunner ◽  
G. Abstreiter
Keyword(s):  
Growth Conditions ◽  
Repulsive Interaction ◽  
Vicinal Surfaces ◽  
Step Bunching ◽  
Weak Ordering ◽  
Efficient Control ◽  
Relative Arrangement ◽  
Typical Period ◽  
Ripple Period ◽  
Self Assembled

AbstractTwo-dimensionally ordered arrays of Ge islands are realized by molecular beam epitaxy on vicinal Si(001) surfaces with regular ripples. Deposition of a 2.5 nm Si0.55Ge0.45/10 nm Si multilayer on vicinal Si(001) surfaces gives rise to the formation of regular ripples with a typical period of 100 nm, due to step-bunching. The ripples lead to the long-range line-up of the Ge islands along their direction, while the strong repulsive interaction between the dense Ge islands determines their relative arrangement on different step bunches of a ripple. The ordering pattern can be controlled by the Ge coverage as well as the direction of the ripples. The Ge islands show a narrow size distribution with the lateral size limited by the ripple periodIn contrast, when deposited directly on well-prepared biatomic-stepped vicinal Si(001) surfaces under the same growth conditions, only weak ordering of Ge islands along the step direction is achieved. No ordering of Ge islands has been observed, when a flat Si(001) surface is employed, where no obvious step-bunching occurs.The results promise efficient control on the position and size of self-assembled and selfordered Ge islands by the steps prepared on vicinal surfaces.

Self-assembled quantum dots and nanoholes by molecular beam epitaxial growth and atomically precise in situ etching

2002 ◽  
Vol 722 ◽  
Author(s):  
S. Kiravittaya ◽  
R. Songmuang ◽  
O. G. Schmidt
Keyword(s):  
Quantum Dots ◽  
Molecular Beam ◽  
Flat Surface ◽  
Local Strain ◽  
Growth Conditions ◽  
Etching Depth ◽  
Molecular Beam Epitaxial ◽  
Self Assembled ◽  
Molecular Beam Epitaxial Growth

AbstractEnsembles of homogeneous self-assembled quantum dots (QDs) and nanoholes are fabricated using molecular beam epitaxy in combination with atomically precise in situ etching. Self-assembled InAs QDs with height fluctuations of ±5% were grown using a very low indium growth rate on GaAs (001) substrate. If these dots are capped with GaAs at low temperature, strong room temperature emission at 1.3 νm with a linewidth of 21 meV from the islands is observed. Subsequently, we fabricate homogeneous arrays of nanoholes by in situ etching the GaAs surface of the capped InAs QDs with AsBr3. The depths of the nanoholes can be tuned over a range of 1-6 nm depending on the nominal etching depth and the initial capping layer thickness. We appoint the formation of nanoholes to a pronounced selectivity of the AsBr3 to local strain fields. The holes can be filled with InAs again such that an atomically flat surface is recovered. QDs in the second layer preferentially form at those sites, where the holes were initially created. Growth conditions for the second InAs layer can be chosen in such a way that lateral QD molecules form on a flat surface.

scholarly journals Scaling laws for step bunching on vicinal surfaces: Role of the dynamical and chemical effects

2021 ◽  
Vol 104 (3) ◽  
Author(s):  
L. Benoit–Maréchal ◽  
M. E. Jabbour ◽  
N. Triantafyllidis
Keyword(s):  
Scaling Laws ◽  
Vicinal Surfaces ◽  
Step Bunching ◽  
Chemical Effects

4H-SiC Homoepitaxial Growth on Vicinal-Off Angled Si-Face Substrate

2010 ◽  
Vol 645-648 ◽  
pp. 99-102 ◽  
Author(s):  
Kazutoshi Kojima ◽  
Sachiko Ito ◽  
Junji Senzaki ◽  
Hajime Okumura
Keyword(s):  
Surface Morphology ◽  
Epitaxial Growth ◽  
Growth Temperature ◽  
Growth Conditions ◽  
Step Bunching ◽  
Homoepitaxial Growth ◽  
Blocking Voltage ◽  
Basal Plane Dislocation ◽  
Epilayer Surface

We have carried out detailed investigations of 4H-SiC homoepitaxial growth on vicinal off-angled Si-face substrates. We found that the surface morphology of the substrate just after in-situ H2 etching was also affected by the value of the vicinal-off angle. Growth conditions consisting of a low C/Si ratio and a low growth temperature were effective in suppressing macro step bunching at the grown epilayer surface. We also demonstrated epitaxial growth without step bunching on a 2-inch 4H-SiC Si-face substrate with a vicinal off angle of 0.79o. Ni Schottky barrier diodes fabricated on an as-grown epilayer had a blocking voltage above 1000V and a leakage current of less than 5x10-7A/cm2. We also investigated the propagation of basal plane dislocation from the vicinal off angled substrate into the epitaxial layer.

scholarly journals Unification of step bunching phenomena on vicinal surfaces

2007 ◽  
Vol 76 (3) ◽  
Author(s):  
Pak-Wing Fok ◽  
Rodolfo R. Rosales ◽  
Dionisios Margetis
Keyword(s):  
Vicinal Surfaces ◽  
Step Bunching

scholarly journals Step-bunching transitions on vicinal surfaces with attractive step interactions

2000 ◽  
Vol 467 (1-3) ◽  
pp. 58-84 ◽  
Author(s):  
V.B. Shenoy ◽  
Shiwei Zhang ◽  
W.F. Saam
Keyword(s):  
Vicinal Surfaces ◽  
Step Bunching

Self-Assembly of Proteins into Three-Dimensional Structures Using Bio-Conjugation

2014 ◽  
Vol 1663 ◽  
Author(s):  
Garima Thakur ◽  
Kovur Prashanthi ◽  
Thomas Thundat
Keyword(s):  
Self Assembly ◽  
Three Dimensional ◽  
Gold Surface ◽  
Building Blocks ◽  
Growth Conditions ◽  
Base Layer ◽  
Chemical Structures ◽  
Molecular Building Blocks ◽  
Ring Structures ◽  
Self Assembled

ABSTRACTSelf–assembly of molecular building blocks provides an interesting route to produce well-defined chemical structures. Tailoring the functionalities on the building blocks and controlling the time of self-assembly could control the properties as well as the structure of the resultant patterns. Spontaneous self-assembly of biomolecules can generate bio-interfaces for myriad of potential applications. Here we report self-assembled patterning of human serum albumin (HSA) protein in to ring structures on a polyethylene glycol (PEG) modified gold surface. The structure of the self-assembled protein molecules and kinetics of structure formation entirely revolved around controlling the nucleation of the base layer. The formation of different sizes of ring patterns is attributed to growth conditions of the PEG islands for bio-conjugation. These assemblies might be beneficial in forming structurally ordered architectures of active proteins such as HSA or other globular proteins.

Step bunching in InGaAs/GaAs quantum wells grown by molecular beam epitaxy on GaAs(001) vicinal surfaces

2001 ◽  
Vol 227-228 ◽  
pp. 46-50 ◽  
Author(s):  
S Martini ◽  
A.A Quivy ◽  
D Ugarte ◽  
C Lange ◽  
W Richter ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Quantum Wells ◽  
Molecular Beam ◽  
Vicinal Surfaces ◽  
Step Bunching

Influence of H2 Preconditioning on the Nucleation and Growth of Self-Assembled Germanium Islands on Silicon (001)

2004 ◽  
Vol 820 ◽  
Author(s):  
Gabriela D.M. Dilliway ◽  
Nicholas E.B. Cowern ◽  
Lu Xu ◽  
Patrick J. McNally ◽  
Chris Jeynes ◽  
...  
Keyword(s):  
Size Distribution ◽  
Self Assembly ◽  
Surface Coverage ◽  
Rutherford Backscattering Spectrometry ◽  
Chemical Vapour ◽  
Growth Conditions ◽  
Island Size ◽  
Practical Applications ◽  
Compositional Evolution ◽  
Self Assembled

AbstractUnderstanding the effects of growth conditions on the process of self-organisation of Ge nanostructures on Si is a key requirement for their practical applications. In this study we investigate the effect of preconditioning with a high-temperature hydrogenation step on the nucleation and subsequent temporal evolution of Ge self-assembled islands on Si (001). Two sets of structures, with and without H2 preconditioning, were grown by low pressure chemical vapour deposition (LPCVD) at 650°C. Their structural and compositional evolution was characterised by Rutherford backscattering spectrometry (RBS), atomic force microscopy (AFM) and micro-Raman (νRaman) spectroscopy. In the absence of preconditioning, we observe the known evolution of self-assembled Ge nanostructures on Si (001), from small islands with a narrow size distribution, to a bimodal size distribution, through to large islands. Surface coverage and island size increase steadily as a function of deposition time. On the H2 preconditioned surface, however, both nucleation rates and surface coverage are greatly increased during the early stages of self-assembly. After the first five seconds, the density of the islands is twice that on the unconditioned surface, and the mean island size is also larger, but the subsequent evolution is much slower than in the case of the unconditioned surface. This retardation correlates with a relatively high measured stress within the islands. Our results demonstrate that standard processes used during growth, like H2 preconditioning, can yield dramatic changes in the uniformity and distribution of Ge nanostructures self-assembled on Si.

Mini droplets to super droplets: evolution of self-assembled Au droplets on GaAs(111)B and (110)

2014 ◽  
Vol 47 (2) ◽  
pp. 505-510 ◽  
Author(s):  
Mao Sui ◽  
Ming-Yu Li ◽  
Eun-Soo Kim ◽  
Jihoon Lee
Keyword(s):  
Growth Parameters ◽  
Average Diameter ◽  
Growth Conditions ◽  
Average Density ◽  
Minor Effect ◽  
Average Height ◽  
Deposition Amount ◽  
Self Assembled ◽  
A Minor ◽  
20 Nm

In this article, the effect of deposition amount on self-assembled Au droplets fabricated on GaAs(111)B and (110) is presented. The investigation is systematically performed by the variation of the Au deposition amount from 2 to 20 nm while fixing the other growth parameters such as annealing temperature and duration to clearly observe the effect. Under identical growth conditions, the self-assembled Au droplets show significantly different size and density depending on the amount of Au deposition:i.e.the average height varies by 436% from 21.8 to 95.5 nm and the average diameter swings by 827% from 52 to 430 nm, showing that the size increase is dominated by the lateral expansion. Meanwhile the average density varies by over two orders of magnitude from 1.24 × 108to 4.48 × 1010 cm−2on GaAs(111)B. With relatively low Au deposition amounts, below 3 nm, round dome-shaped mini Au droplets with high packing density can be fabricated, while super large Au droplets result with higher deposition amounts, above 10 nm, with a density two orders of magnitude lower. It is also found that the surface index has a minor effect on the fabrication of self-assembled Au droplets with the variation of deposition amount. The results are systematically analyzed and discussed in terms of atomic force microscopy and scanning electron microscopy images, line profiles, power spectrums, r.m.s. surface roughness, and size and density plots.

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