GROWTH OF Ge ON In-ADSORBED Si(111) SURFACES STUDIED BY UHV-REM

1995 ◽  
Vol 02 (01) ◽  
pp. 1-8 ◽  
Author(s):  
H. MINODA ◽  
Y. TANISHIRO ◽  
N. YAMAMOTO ◽  
K. YAGI
Keyword(s):  
Surface Structure ◽  
Surface Diffusion ◽  
Critical Thickness ◽  
Three Dimensional ◽  
Layer Growth ◽  
Text Structure ◽  
Surface Structures ◽  
Growth Mode ◽  
Island Growth ◽  
Island Nucleation

Growth of Ge on In-adsorbed Si (111)[Formula: see text] and 4×1 surfaces was studied by REM-RHEED. Indium atoms were segregated to the topmost surface during Ge deposition. The formation of the 1×1 structure, which is one of the In-adsorbed structures on the Ge (111) surface, was observed on both the [Formula: see text] structure and the 4×1 surface structures. Suppression of two- and three-dimensional island nucleation of Ge by In predeposition was noticed below 430°C on both surface structures. The critical thickness at which the layer growth mode changed to the island growth mode on the 4×1 surface structure was larger than that on the [Formula: see text] surface structure. Apparent surface diffusion lengths of Ge changed after 2 ML deposition of Ge on the [Formula: see text] surface structure.

Segregation and Interdiffusion of in Atoms in GaAs/InAs/GaAs Heterostructures

1993 ◽  
Vol 312 ◽  
Author(s):  
T. Kawai ◽  
H. Yonezu ◽  
Y. Ogasawara ◽  
D. Saito ◽  
K. Pak
Keyword(s):  
Growth Temperature ◽  
Three Dimensional ◽  
Film Surface ◽  
Growth Direction ◽  
Layer Growth ◽  
Growth Mode ◽  
Layer By Layer ◽  
Island Growth ◽  
Alas Layer ◽  
Secondary Ion

AbstractThe segregation and interdiffusion of In atoms in the GaAs/InAs/GaAs heterostructures were investigated by secondary ion mass spectroscopy. When the 1 ML thick InAs layer was grown in a layer-by-layer growth mode with no dislocations, the segregation of In atoms became marked with the increase of the growth temperature. However, the segregation was observed even at relatively low growth temperature of 400°C in molecular beam epitaxy. It was found that the segregation was markedly enhanced by dislocations near the heterointerface when the thick InAs layers were grown in a three-dimensional island growth mode. The interdiffusion of In atoms toward the growth direction occurred after thermal annealing, which could be assisted by vacancies propagating from the film surface into epilayer. It became apparent that the interdiffusion was effectively suppressed by a thin AlAs layer inserted in the GaAs cap layer.

Hierarchical Nano/Micro-structured Surfaces with High Surface Area/Volume Ratios

2021 ◽  
pp. 1-36
Author(s):  
Ketki Lichade ◽  
Yizhou Jiang ◽  
Yayue Pan
Keyword(s):  
Surface Structure ◽  
Surface Area ◽  
Light Trapping ◽  
High Surface ◽  
High Surface Area ◽  
Three Dimensional ◽  
Structure Design ◽  
Surface Structures ◽  
Structured Surfaces ◽  
Design And Manufacture

Abstract Recently, many studies have investigated additive manufacturing of hierarchical surfaces with high surface area/volume (SA/V) ratios, and their performance has been characterized for applications in next-generation functional devices. Despite recent advances, it remains challenging to design and manufacture high SA/V ratio structures with desired functionalities. In this study, we established the complex correlations among the SA/V ratio, surface structure geometry, functionality, and manufacturability in the Two-Photon Polymerization (TPP) process. Inspired by numerous natural structures, we proposed a 3-level hierarchical structure design along with the mathematical modeling of the SA/V ratio. Geometric and manufacturing constraints were modeled to create well-defined three-dimensional hierarchically structured surfaces with a high accuracy. A process flowchart was developed to design the proposed surface structures to achieve the target functionality, SA/V ratio, and geometric accuracy. Surfaces with varied SA/V ratios and hierarchy levels were designed and printed. The wettability and antireflection properties of the fabricated surfaces were characterized. It was observed that the wetting and antireflection properties of the 3-level design could be easily tailored by adjusting the design parameter settings and hierarchy levels. Furthermore, the proposed surface structure could change a naturally-hydrophilic surface to near-superhydrophobic. Geometrical light trapping effects were enabled and the antireflection property could be significantly enhanced (>80% less reflection) by the proposed hierarchical surface structures. Experimental results implied the great potential of the proposed surface structures for various applications such as microfluidics, optics, energy, and interfaces.

scholarly journals Initial Growth and Crystallization Onset of Plasma Enhanced-Atomic Layer Deposited ZnO

Crystals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 291
Author(s):  
Alberto Perrotta ◽  
Julian Pilz ◽  
Roland Resel ◽  
Oliver Werzer ◽  
Anna Maria Coclite
Keyword(s):  
Atomic Layer ◽  
Layer Growth ◽  
Growth Mode ◽  
Ex Situ ◽  
Native Oxide ◽  
Layer By Layer ◽  
Initial Growth ◽  
Island Growth ◽  
X Ray ◽  
Crystallization Onset

Direct plasma enhanced-atomic layer deposition (PE-ALD) is adopted for the growth of ZnO on c-Si with native oxide at room temperature. The initial stages of growth both in terms of thickness evolution and crystallization onset are followed ex-situ by a combination of spectroscopic ellipsometry and X-ray based techniques (diffraction, reflectivity, and fluorescence). Differently from the growth mode usually reported for thermal ALD ZnO (i.e., substrate-inhibited island growth), the effect of plasma surface activation resulted in a substrate-enhanced island growth. A transient region of accelerated island formation was found within the first 2 nm of deposition, resulting in the growth of amorphous ZnO as witnessed with grazing incidence X-ray diffraction. After the islands coalesced and a continuous layer formed, the first crystallites were found to grow, starting the layer-by-layer growth mode. High-temperature ALD ZnO layers were also investigated in terms of crystallization onset, showing that layers are amorphous up to a thickness of 3 nm, irrespective of the deposition temperature and growth orientation.

Dislocation Behaviour in GexSi1-x Epilayers on (001)Si

1989 ◽  
Vol 160 ◽  
Author(s):  
Eric P. Kvam ◽  
D.M. Maher ◽  
C.J. Humphreys
Keyword(s):  
Dislocation Density ◽  
Film Thickness ◽  
Critical Thickness ◽  
Three Dimensional ◽  
Critical Value ◽  
Misfit Dislocations ◽  
Island Growth ◽  
Edge Type ◽  
Dislocation Behaviour ◽  
Step Mechanism

AbstractWe have observed that the nature of misfit dislocations introduced near the critical thickness in GexSi1-x alloys on (001)Si changes markedly in the region 0.4 ≤ x ≤ 0.5. At or below the lower end of this compositional range, the observed microstructure is comprised almost entirely of 60° type dislocations, while at the high end, the dislocation structure is almost entirely Lomer edge type. Concurrent with this change, the dislocation density at the top of the epilayer varies by a factor of about 60X. Similarly, several other observables (e.g. dislocation length and spacing) also change appreciably.Part of the reason for the morphological variation seems to be a change in the source for dislocation introduction, in conjunction with a change in glide behaviour of dislocations as a function of film thickness. Evidence will be presented that indicates strain, as well as thickness, has a critical value for some dislocation introduction mechanisms, and that these together determine the resulting microstructure.Furthermore, it appears unlikely that the edge-type Lomer dislocations which appear at about x = 0.5 are either introduced directly, by climb, or grown in, as in the three-dimensional island growth and coalescence which occurs when x approaches unity. Instead, a two-step mechanism involving glissile dislocations is proposed and discussed.

Effects of Stress on Step Energies and Surface Roughness

MRS Bulletin ◽  
1996 ◽  
Vol 21 (4) ◽  
pp. 27-30 ◽  
Author(s):  
Christopher Roland
Keyword(s):  
Thin Films ◽  
Strain Relaxation ◽  
Three Dimensional ◽  
Layer Growth ◽  
Growth Mode ◽  
Misfit Dislocations ◽  
Layer By Layer ◽  
Strained Layers ◽  
The Subject ◽  
Growth Changes

Strain relaxation in lattice-mismatched, heteroepitaxial systems is one of the classic problems in materials physics, which has gained new urgency with the increased applications of strained layers in microelectronic systems. In general both the structure and the integrity of the thin films are strongly influenced by strain. For instance it has long been known that under strain, the growth changes from an initial layer-by-layer growth mode to one with three-dimensional islanding. In the seminal works of van der Merwe, and Matthews and Blakeslee, this change in growth mode is explained in terms of the introduction of strain-relieving misfit dislocations, which appear when the film has reached some critical thickness. Recently it has become clear that this change in growth mode can take place even without the introduction of misfit dislocations. Such dislocation-free coherent islanding, or “roughening,” has been observed experimentally both in Ge/Si and in InGaAs/GaAs systems. Furthermore recent experiments show that in Ge/Si(100) systems, the thin films display a curious asymmetry with respect to the sign of the strain: Films under compression roughen by forming coherent islands while those under tension remain relatively smooth. A possible mechanism behind this strain-induced type of roughening is the subject of this article.

scholarly journals MESOSCOPIC SCALE OBSERVATIONS OF SURFACE ALLOYING, SURFACE PHASE TRANSITIONS, DOMAIN COARSENING, AND 3D ISLAND GROWTH: Pb on Cu(100)

2000 ◽  
Vol 07 (05n06) ◽  
pp. 649-655 ◽  
Author(s):  
G. L. KELLOGG ◽  
R. A. PLASS
Keyword(s):  
Phase Transitions ◽  
Three Dimensional ◽  
Text Structure ◽  
Surface Alloying ◽  
Island Growth ◽  
Mesoscopic Scale ◽  
First Order ◽  
Surface Phase Transitions ◽  
Proposed Model ◽  
Low Energy Electron

Low energy electron microscopy (LEEM) is used to investigate the dynamics of Pb overlayer growth on Cu(100). By following changes in surface morphology during Pb deposition, we measure the amount of Cu transported to the surface as the Pb first alloys into the surface during formation of the c(4×4) phase and subsequently dealloys during conversion to the c(2×2) phase. We find that the added coverage of Cu during alloying is consistent with the proposed model for the c(4×4) alloy phase, but the added coverage during dealloying is not consistent with the accepted model for the c(2×2) phase. To account for the discrepancy, we propose that Cu atoms are incorporated in the c(2×2) structure. Island growth and step advancement during the transition from the c(2×2) to [Formula: see text] structure agrees with this model. We also use LEEM to identify the order and temperature of the two-dimensional melting phase transitions for the three Pb/Cu(100) surface structures. Phase transitions for the [Formula: see text] and c(4×4) structures are first-order, but the c(2×2) transition is second-order. We determine that rotational domains of the [Formula: see text] structure coarsen from nanometer- to micron-sized dimensions with relatively mild heating (~ 120°C), whereas coarsening of c(4×4) domain requires considerably higher temperatures (~ 400°C). In studies of three-dimensional island formation, we find that the islands grow asymmetrically with an orientational dependence that is directly correlated with the domain structure of the underlying [Formula: see text] phase.

Oxygen Pressure Dependence of Morphology of Morphology of La2-xSrxCuO4 Ultra-Thin Films

1997 ◽  
Vol 11 (21n22) ◽  
pp. 981-987
Author(s):  
H. Q. Yin ◽  
T. Arakawa ◽  
Y. Kaneda ◽  
T. Yoshikawa ◽  
N. Haneji ◽  
...  
Keyword(s):  
Thin Films ◽  
Pressure Dependence ◽  
Film Growth ◽  
Ambient Pressure ◽  
High Energy ◽  
Layer Growth ◽  
Growth Mode ◽  
Layer By Layer ◽  
Island Growth ◽  
Experimental Conditions

La 2-x Sr x CuO 4 ultra-thin films with thickness 200 Å were fabricated by pulsed laser deposition method in oxygen ( O 2) atmosphere. The morphology of deposited films was investigated by reflection high energy electron diffraction (RHEED), atomic force microscopy (AFM) and scanning electronic microscopy (SEM). The strong oxygen ambient pressure dependence of film morphology was observed. In high oxygen ambient pressure, the film growth is dominated by island growth mode. The results imply that the experimental conditions of oxygen ambient pressure and substrate temperature are critical for the layer-by-layer growth mode.

Pressure-Controlled GaN MBE Growth Using a Hollow Anode Nitrogen Ion Source

1996 ◽  
Vol 449 ◽  
Author(s):  
M. S. H. Leung ◽  
R. Klockenbrink ◽  
C. Kisielowski ◽  
H. Fujii ◽  
J. Krüger ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Layer Growth ◽  
Ion Source ◽  
Growth Mode ◽  
Mbe Growth ◽  
Hollow Anode ◽  
Cubic Gan ◽  
Dimensional Growth ◽  
Nitrogen Ion ◽  
Pressure Controlled

ABSTRACTGaN films were grown on sapphire substrates at temperatures below 1000 K utilizing a Hollow Anode nitrogen ion source. A Ga flux limited growth rate of ~ 0.5 µm/h is demonstrated. Active utilization of strain and the assistance of a nitrogen partial pressure during buffer layer growth are found to be crucial issues that can improve the film quality. The best films exhibit a full width at half maximum of the x-ray rocking curves of 80 arcsec and 1.85 meV for the excitonic photoluminescence measured at 4 K. A Volmer-Weber three dimensional growth mode and the spontaneous formation of cubic GaN inclusions in the hexagonal matrix are observed in the investigated growth temperature range. It is argued that this growth mode contributes to a limitation of the carrier mobility in these films that did not exceed 120 cm2/Vs though a minimum carrier concentration of ~ 1015 cm−3 was achieved.

Critical Thickness for Three-Dimensional Epitaxial Island Growth

1988 ◽  
Vol 130 ◽  
Author(s):  
K. Jagannadham ◽  
J. Narayan
Keyword(s):  
Dislocation Loop ◽  
Misfit Dislocation ◽  
Critical Thickness ◽  
Three Dimensional ◽  
Surface Boundary ◽  
Dislocation Loops ◽  
Island Growth ◽  
Interfacial Dislocation ◽  
Burgers Vector ◽  
Surface Boundary Conditions

AbstractThe generation of misfit dislocation loops in three-dimensional epitaxial islands grown on thick substrates is analyzed. The coherent strain in the island is described by virtual interfacial dislocation loops situated in the interface. The traction free surface boundary conditions are satisfied by the surface dislocation loops situated on the surface of the island. A misfit dislocation loop is formed and the changes in the energy of the configuration used to determine if the total energy is lowered. The numerical analysis is carried out forhemispherical islands of GaAs grown on (100) silicon with a misfit dislocation of Burgers vector 3.84 Å. It has been found energetically favorable to nucleate a misfit dislocation loop at a distance of 3 å from the interface when the radius of the hemispherical island is equal to or greater than 40 å. In addition, a misfit dislocation loop could be nucleated at a larger distance from the interface when the size of the island is larger.

Nucleation and Growth of Ultrathin Epitaxial Metal Silicides on Silicon

1987 ◽  
Vol 102 ◽  
Author(s):  
J. L. Batstone ◽  
R. T. Tung ◽  
Julia M. Phillips ◽  
J. M. Gibson
Keyword(s):  
Three Dimensional ◽  
Contact Angles ◽  
Translation Vector ◽  
Island Growth ◽  
Island Nucleation ◽  
High Temperature Reaction ◽  
Transmission Electron ◽  
Metal Silicides ◽  
Dimensional Growth ◽  
The Difference

ABSTRACTGrowth of epitaxial single crystal nickel and cobalt disilicide films on silicon is performed under UHV conditions by deposition of Co or Ni on silicon followed by a high temperature reaction to form the silicide. The uniformity and perfection of ultrathin epitaxial layers has been studied using transmission electron microscopy. Mechanisms controlling island growth are discussed. Island nucleation observed in pseudomorphic films of NiSi2 /Si(100) (∼60Å thick) is shown to be the result of the difference in symmetry between the NiSi2 and Si. Islands related by a translation vector a/4<111> show an equilibrium island separation of 15±1.5Å. The boundary between islands is described as a coreless defect. In comparison,, pseudomorphic layers of CoSi2 /Si(111) are observed up to thicknesses ∼30Å. Pinholes are commonly observed in CoSi2 /Si(111) thin films. Finite contact angles (∼50) between substrate and deposit suggest a desire for three-dimensional growth under equilibrium conditions.

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