Substrate-Surface Effect on Initial Growth Process of Microcrystalline Silicon Films

AbstractInitial growth processes of hydrogenated microcrystalline silicon (μc-Si:H) films have been investigated by scanning tunneling microscopy (STM), high-resolution transmission electron microscopy (HRTEM), and reflection high energy electron diffraction (RHEED). The μc-Si:H films were prepared by plasma enhanced chemical vapor deposition (PECVD) on H-terminated Si(111) and plasma-oxidized SiO2/Si(111) surfaces that were made atomically-flat by a careful wet processing. On H-terminated Si(111) the initial growth was epitaxial as evidenced by HRTEM and RHEED, while on SiO2/Si(111) the initial process was nucleation of amorphous Si followed by formation of randomly oriented μc-Si:H structure. STM observation revealed that, on both H-terminated and SiO2-terminated surfaces, initial growth processes proceed through the nucleation-and-coalescence mechanism.

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Growth of Laser Ablated YBa2Cu3O7−δ Films as Examined by Rheed and Scanning Tunneling Microscopy

MRS Proceedings ◽

10.1557/proc-285-305 ◽

1992 ◽

Vol 285 ◽

Cited By ~ 9

Author(s):

Stephen E. Russek ◽

Alexana Roshko ◽

Steven C. Sanders ◽

David A. Rudman ◽

J. W. Ekin ◽

...

Keyword(s):

Surface Roughness ◽

Scanning Tunneling Microscopy ◽

Three Dimensional ◽

High Energy ◽

Spiral Growth ◽

Scanning Tunneling ◽

Initial Growth ◽

Rheed Pattern ◽

Island Growth ◽

Tunneling Microscopy

ABSTRACTUsing scanning tunneling microscopy (STM) and reflection high energy electron diffraction (RHEED) we have examined the growth morphology, surface structure, and surface degradation of laser ablated YBa2Cu3O7−δ thin films. Films from 5 nm to ltm thick were studied. The films were deposited on MgO and LaAlO3 substrates using two different excimer laser ablation systems. Both island nucleated and spiral growth morphologies were observed depending on the substrate material and deposition rate used. The initial growth mechanism observed for a 5–10 nm thick film is replicated through different growth layers up to thicknesses of 200 run. Beyond 200 rnm, the films show some a-axis grains and other outgrowths. The thinnest films (5–10 nm) show considerable surface roughness on the order of 3–4 nm. For both growth mechanisms the ledge width remains approximately constant (∼ 30 nm) and the surface roughness increases as the film thickness increases. The films with spiral growth have streaked RHEED patterns despite having considerable surface roughness, while the films with island growth have more of a three dimensional diffraction pattern. RHEED patterns were obtained after the film surfaces were degraded by exposure to air, KOH developer, a Br-methanol etch, and a shallow ion mill. Exposure to air and KOH developer caused only moderate degradation of the RHEED pattern whereas a shallow (I nm deep) 300 V ion mill completely destroyed the RHEED pattern.

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Structural Evolution During the Initial Epitaxial Growth of Moon on Sapphire

MRS Proceedings ◽

10.1557/proc-584-71 ◽

1999 ◽

Vol 584 ◽

Author(s):

P. A. Ryan ◽

F. Tsui

Keyword(s):

Epitaxial Growth ◽

Structural Evolution ◽

Lattice Relaxation ◽

High Energy ◽

Layer Growth ◽

Scanning Tunneling ◽

Layer By Layer ◽

Initial Growth ◽

Tunneling Microscopy ◽

Length Scales

AbstractStructural evolution during initial epitaxial growth of Mo (111) and (110) on Al2O3 substrates has been studied using real-time reflection high energy electron diffraction and in-situ scanning tunneling microscopy. The Mo (111) growth on sapphire (0001) is initiated by the formation of small mound-like 3-dimensional (3D) islands that are correlated with unique length scales. The observed surface length scales depend on growth temperature and rate, and they coarsen as the thickness increases. The initial growth of Mo (110) on sapphire (1120) begins with layer-by-layer growth for the first monolayer, and subsequently the growth is 3D with mound-like features that are larger than those corresponding (111) counterparts. In both orientations lattice relaxation occurs within the first 2 – 3 monolayers.

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Influence of Surface Structure on Epitaxial Growth of Si on Si(111)-(7 × 7) Substrate

Surface Review and Letters ◽

10.1142/s0218625x98001237 ◽

1998 ◽

Vol 05 (03n04) ◽

pp. 865-872 ◽

Cited By ~ 19

Author(s):

Yukichi Shigeta

Keyword(s):

Surface Structure ◽

Epitaxial Growth ◽

High Energy ◽

Layer Growth ◽

Scanning Tunneling ◽

Layer By Layer ◽

Initial Growth ◽

Lateral Growth ◽

Tunneling Microscopy ◽

Starting Point

To make clear the influence of surface structure on epitaxial growth, we have studied the growth of Si on a Si(111)-(7 × 7) superlattice surface by using scanning tunneling microscopy and reflection high energy electron diffraction. In the initial growth stage on the 7 × 7 superlattice, multilayer islands are formed because lateral growth of the first layer is prevented by the stable 7 × 7 structure and some migrating atoms climb up the first layer and nucleate on it. However, lateral growth of the second layer on the first one is not prevented and the layer-by-layer growth starts, because the structure of the first layer is composed of small domains with some metastable surface structures, which is rather easier to rearrange than the 7 × 7 structure. The starting point of the layer-by-layer growth depends on the substrate temperature, because the surface structure formed on a growing layer is influenced by the temperature. We obtained the result that the nucleation of a two-dimensional island on the 7 × 7 superlattice is also influenced by the surface structure. The island, whose size is less than the half-unit of the 7 × 7 structure, is unstable. The result suggests that, for the nucleation on the stable surface structure, the activation energy of rearrangement of the surfue structure should be taken into the consideration of the formation energy of the nucleus.

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STM Observation on the Initial growth of Amorphous and Microcrystalline Silicon Films

MRS Proceedings ◽

10.1557/proc-420-413 ◽

1996 ◽

Vol 420 ◽

Cited By ~ 17

Author(s):

K. Ikuta ◽

Y. Toyoshima ◽

S. Yamasaki ◽

A. Matsuda ◽

K. Tanaka

Keyword(s):

Graphite Substrate ◽

Scanning Tunneling ◽

Initial Growth ◽

Microcrystalline Silicon ◽

Tunneling Microscopy ◽

Raman Scattering Spectroscopy ◽

Gas Plasma ◽

Nucleation Sites ◽

Initial Stage ◽

The Difference

AbstractDirect nanoscale observation on the nucleation and growth of hydrogenated amorphous and microcrystalline silicon on graphite substrates was made using scanning tunneling microscopy, atomic force microscopy, and Raman scattering spectroscopy. Nucleation of hydrogenated silicon clusters is initiated through the nucleation sites created by reactive hydrogen species coming from the source gas plasma. The difference in spatial distribution of nucleated clusters at the initial stage of deposition between a-Si:H and μc-Si:H is ascribed to the difference in the number density of nucleation sites which results in difference in the diffusion length of a SiH3 radical at the initial stage of deposition on the graphite substrate. The RMS roughness of μc-Si:H films is larger than that of a-Si:H when the film thickness is larger than 10 Å, which is opposite to the behavior at the initial nucleation stage on the graphite substrate.

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STM studies of crystal growth

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100086179 ◽

1991 ◽

Vol 49 ◽

pp. 374-375

Author(s):

M. G. Lagally

Keyword(s):

Crystal Growth ◽

Molecular Beam ◽

Chemical Vapor ◽

Sputter Deposition ◽

Field Of View ◽

Scanning Tunneling ◽

Wide Field ◽

Tunneling Microscopy ◽

Wide Field Of View ◽

The One

It has been recognized since the earliest days of crystal growth that kinetic processes of all Kinds control the nature of the growth. As the technology of crystal growth has become ever more refined, with the advent of such atomistic processes as molecular beam epitaxy, chemical vapor deposition, sputter deposition, and plasma enhanced techniques for the creation of “crystals” as little as one or a few atomic layers thick, multilayer structures, and novel materials combinations, the need to understand the mechanisms controlling the growth process is becoming more critical. Unfortunately, available techniques have not lent themselves well to obtaining a truly microscopic picture of such processes. Because of its atomic resolution on the one hand, and the achievable wide field of view on the other (of the order of micrometers) scanning tunneling microscopy (STM) gives us this opportunity. In this talk, we briefly review the types of growth kinetics measurements that can be made using STM. The use of STM for studies of kinetics is one of the more recent applications of what is itself still a very young field.

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Scanning tunneling microscopy of E. coli RNA polymerase deposited onto an Au substrate by an electrochemical process

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100086192 ◽

1991 ◽

Vol 49 ◽

pp. 378-379

Author(s):

Rebecca W. Keller ◽

Carlos Bustamante ◽

David Bear

Keyword(s):

Scanning Tunneling Microscope ◽

Biological Sample ◽

Substrate Surface ◽

Electrochemical Process ◽

Atomic Resolution ◽

Scanning Tunneling ◽

Tunneling Microscopy ◽

Tunneling Microscope ◽

E Coli ◽

Preparation Techniques

Under ideal conditions, the Scanning Tunneling Microscope (STM) can create atomic resolution images of different kinds of samples. The STM can also be operated in a variety of non-vacuum environments. Because of its potentially high resolution and flexibility of operation, it is now being applied to image biological systems. Several groups have communicated the imaging of double and single stranded DNA.However, reproducibility is still the main problem with most STM results on biological samples. One source of irreproducibility is unreliable sample preparation techniques. Traditional deposition methods used in electron microscopy, such as glow discharge and spreading techniques, do not appear to work with STM. It seems that these techniques do not fix the biological sample strongly enough to the substrate surface. There is now evidence that there are strong forces between the STM tip and the sample and, unless the sample is strongly bound to the surface, it can be swept aside by the tip.

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Room temperature observation of the correlation between atomic and electronic structure of graphene on Cu(110)

RSC Advances ◽

10.1039/c6ra13058e ◽

2016 ◽

Vol 6 (100) ◽

pp. 98001-98009 ◽

Cited By ~ 2

Author(s):

Thais Chagas ◽

Thiago H. R. Cunha ◽

Matheus J. S. Matos ◽

Diogo D. dos Reis ◽

Karolline A. S. Araujo ◽

...

Keyword(s):

Electronic Structure ◽

Chemical Vapor Deposition ◽

Scanning Tunneling Microscopy ◽

Vapor Deposition ◽

Room Temperature ◽

Chemical Vapor ◽

Scanning Tunneling ◽

Tunneling Microscopy ◽

Temperature Observation ◽

Atomic And Electronic Structure

We have used atomically-resolved scanning tunneling microscopy and spectroscopy to study the interplay between the atomic and electronic structure of graphene formed on copper via chemical vapor deposition.

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Templated quasicrystalline ordering of single elements and molecules

Acta Crystallographica Section A Foundations and Advances ◽

10.1107/s2053273314099185 ◽

2014 ◽

Vol 70 (a1) ◽

pp. C81-C81

Author(s):

H. R. Sharma ◽

J. A. Smerdon ◽

K. Nozawa ◽

K. M. Young ◽

T. P. Yadav ◽

...

Keyword(s):

Substrate Surface ◽

Chemical Properties ◽

Scanning Tunneling ◽

Three Dimension ◽

Tunneling Microscopy ◽

Quantum Size ◽

Adsorption Energies ◽

Molecular Layers ◽

Physical And Chemical ◽

The Impact

We have used quasicrystals as templates for the exploration of new epitaxial phenomena. Several interesting results have been observed in the growth on surfaces of the common Al-based quasicrystals [1]. These include pseudomorphic monolayers, quasiperiodically modulated multilayer structures, and fivefold-twinned islands with magic heights influenced by quantum size effects [1]. Here we present our recent works on the growth of various elements and molecules on a new substrate, icosahedral (i) Ag-In-Yb quasicrystal, which have resulted in various epitaxial phenomena not observed previously. The growth of Pb on the five-fold surface of i-Ag-In-Yb yields a film which possesses quasicrystalline ordering in three-dimension [2]. Using scanning tunneling microscopy (STM) and DFT calculations of adsorption energies, we find that lead atoms occupy the positions of atoms in the rhombic triacontahedral (RTH) cluster, the building block of the substrate, and thus grow in layers with different heights and adsorption energies. The adlayer–adlayer interaction is crucial for stabilizing the epitaxial quasicrystalline structure. We will also present the first example of quasicrystalline molecular layers. Pentacene adsorbs at tenfold-symmetric sites of Yb atoms around surface-bisected RTH clusters, yielding quasicrystalline order [3]. Similarly, C-60 growth on the five-fold surface of i-Al-Cu-Fe at elevated temperature produces quasicrystalline layer, where the growth is mediated by Fe atoms on the substrate surface [3]. The finding of quasicrystalline thin films of single elements and molecules opens an avenue for further investigation of the impact of the aperiodic atomic order over periodic order on the physical and chemical properties of materials.

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A New, Nearly Single-Domain Surface Structure of Homoepitaxial Diamondr (001) Films

MRS Proceedings ◽

10.1557/proc-423-433 ◽

1996 ◽

Vol 423 ◽

Cited By ~ 1

Author(s):

Yalei Kuang ◽

Naesung Lee ◽

Andrzej Badzian ◽

Teresa Badzian ◽

Tien T. Tsong

Keyword(s):

Surface Structure ◽

Natural Diamond ◽

Single Layer ◽

Chemical Vapor ◽

Single Domain ◽

Scanning Tunneling ◽

Tunneling Microscopy ◽

Plasma Chemical Vapor Deposition ◽

Boron Doped ◽

Step Edges

AbstractBoron-doped homoepitaxial diamond films were grown on natural diamond (001) substrates using microwave-assisted plasma chemical vapor deposition techniques. The surface structures were investigated using scanning tunneling microscopy (STM). This showed a dimertype 2×1 reconstruction structure with single-layer steps where dimer rows on the upper terrace are normal to or parallel to the step edges. We found that dimer rows parallel to the step edges are much longer than those normal to the step edges. The nearly single-domain surface structure observed by STM is in agreement with the low-energy electron diffraction (LEED) patterns from these surfaces. The high atomic resolution STM image showed that the local 1×1 configurations exist.

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