Wet Etching Methods for Perovskite Substrates

1999 ◽  
Vol 587 ◽  
Author(s):  
Victor Leca ◽  
Guus Rijnders ◽  
Gertjan Koster ◽  
Dave H. A. Blank ◽  
Horst Rogalla
Keyword(s):  
Ph Value ◽  
Substrate Surface ◽  
High Energy ◽  
Etching Time ◽  
Epitaxial Thin Films ◽  
Etch Pits ◽  
High Quality ◽  
Oxide Electronics ◽  
Force Microscopy ◽  
Atomically Flat

AbstractIn oxide electronics substrates with atomically flat terraces are a request for growing high-quality epitaxial thin films. In this paper results on chemical etching of some substrates with perovskite, ABO3, structure (e.g., SrTiO3, LSAT - the (LaAlO3)0.3(Sr2AlTaO6)0.35 solid solution, and NdGaO3) are presented. In order to obtain high quality substrates, different etchants (NH4F + HF, HCl + NH4Cl, and HCl + HNO3) with various pH values have been studied. From Atomic Force Microscopy (AFM), in air, we conclude that, irrespective of the etchant that has been used, a substrate surface with a BOx terminated layer and atomically flat terraces without etch pits could be obtained. The pH-value and temperature of the etchant and the etching time, however, influence significantly the surface quality. Reflection high energy electron diffraction (RHEED) patterns confirmed the AFM results.

Comparative Growth of AIN on Singular and Off-Axis 6H and 4H-SiC by MOCVD

1998 ◽  
Vol 537 ◽  
Author(s):  
S. Wilson ◽  
C. S. Dickens ◽  
J. Griffin ◽  
M. G. Spencer
Keyword(s):  
High Energy ◽  
Two Dimensional ◽  
Comparison Study ◽  
High Energy Electron ◽  
High Quality ◽  
Force Microscopy ◽  
Step Flow ◽  
Atomic Force ◽  
Dimensional Growth ◽  
Atomically Flat

AbstractA comparison study of the growth of aluminum nitride (AIN) single crystal epitaxy on 6H-SiC and 4H-SiC substrates has been performed. The material has been characterized using atomic force microscopy (AFM) and reflective high energy electron diffraction (RHEED). AIN crystals were deposited on the following 6H-SiC substrates: singular with and without an initial SiC epilayer, and 3.5° off-axis with and without an initial SIC epilayer. AIN crystals were deposited on 8.0° off-axis 4H-SiC with and without initial SIC epilayers. AFM shows that the deposition of AIN on 6H-SiC and 4H-SIC with an initial SiC epilayer displays high quality quasi-two dimensional growth as atomically flat or step flow epitaxy.

scholarly journals Comparative Growth of AlN on Singular and Off-Axis 6H and 4H-SiC by MOCVD

1999 ◽  
Vol 4 (S1) ◽  
pp. 344-350
Author(s):  
S. Wilson ◽  
C. S. Dickens ◽  
J. Griffin ◽  
M. G. Spencer
Keyword(s):  
High Energy ◽  
Two Dimensional ◽  
Comparison Study ◽  
High Energy Electron ◽  
High Quality ◽  
Force Microscopy ◽  
Step Flow ◽  
Atomic Force ◽  
Dimensional Growth ◽  
Atomically Flat

A comparison study of the growth of aluminum nitride (AlN) single crystal epitaxy on 6H-SiC and 4H-SiC substrates has been performed. The material has been characterized using atomic force microscopy (AFM) and reflective high energy electron diffraction (RHEED). AlN crystals were deposited on the following 6H-SiC substrates: singular with and without an initial SiC epilayer, and 3.5° off-axis with and without an initial SiC epilayer. AlN crystals were deposited on 8.0° off-axis 4H-SiC with and without initial SiC epilayers. AFM shows that the deposition of AlN on 6H-SiC and 4H-SiC with an initial SiC epilayer displays high quality quasi-two dimensional growth as atomically flat or step flow epitaxy.

scholarly journals Growth of Ordered Graphene Ribbons by Sublimation Epitaxy

Crystals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 449
Author(s):  
Shuxian Cai ◽  
Xingfang Liu ◽  
Xin Zheng ◽  
Zhonghua Liu
Keyword(s):  
Substrate Surface ◽  
Graphene Film ◽  
Graphene Ribbon ◽  
High Quality ◽  
Graphene Layers ◽  
Force Microscopy ◽  
Layer Graphene ◽  
Micro Raman Spectroscopy ◽  
Atomic Force ◽  
Few Layer Graphene

Ordered graphene ribbons were grown on the surface of 4° off-axis 4H-SiC wafers by sublimation epitaxy, and characterized by using scanning electron microscopy (SEM), atomic force microscopy (AFM) and micro-Raman spectroscopy (μ-Raman). SEM showed that there were gray and dark ribbons on the substrate surface, and AFM further revealed that these ordered graphene ribbons had clear stepped morphologies due to surface step-bunching. It was shown by μ-Raman that the numbers of graphene layers of these two types of regions were different. The gray region was composed of mono- or bilayer ordered graphene ribbon, while the dark region was of tri- or few-layer ribbon. Meanwhile, ribbons were all homogeneous and had a width up to 40 μm and a length up to 1000 μm, without micro defects such as grain boundaries, ridges, or mono- and few-layer graphene mixtures. The results of this study are useful for optimized growth of high-quality graphene film on silicon carbide crystal.

scholarly journals All chemical YBa2Cu3O7 superconducting multilayers: Critical role of CeO2 cap layer flatness

2009 ◽  
Vol 24 (4) ◽  
pp. 1446-1455 ◽  
Author(s):  
M. Coll ◽  
J. Gàzquez ◽  
R. Huhne ◽  
B. Holzapfel ◽  
Y. Morilla ◽  
...  
Keyword(s):  
Critical Role ◽  
High Energy ◽  
Buffer Layers ◽  
Solution Deposition ◽  
Ybco Films ◽  
Force Microscopy ◽  
Atomic Force ◽  
Current Densities ◽  
Atomically Flat

New advances toward microstructural improvement of epitaxial CeO2 films grown by chemical solution deposition and their use as buffer layers for YBa2Cu3O7 (YBCO) films are presented. We demonstrate that the degree of epitaxy and the fraction of (001) atomically flat surface area are controlled by the incorporation of tetravalent (Zr4+) or trivalent (Gd3+) cations into the ceria lattice. The degree of epitaxy has been investigated by means of Rutherford backscattering spectroscopy-channeling and reflection high-energy electron diffraction, and a new methodology is also presented to quantify the fraction of (001) atomically flat area from atomic force microscopy images. Results are further correlated with the superconducting properties, microstructure, and texture of YBCO films grown by the trifluoroacetate route. A comparison with pulsed laser deposition and YBCO films grown on the same ceria layers is also presented. This growth procedure has allowed us to obtain all chemical multilayer films with controlled microstructure and critical current densities above 4 MA cm−2 at 77 K.

Deposition of GaN Films on Freestanding CVD Thick Diamond Films

2010 ◽  
Vol 654-656 ◽  
pp. 1740-1743 ◽  
Author(s):  
Dong Zhang ◽  
Yi Zhen Bai ◽  
Fu Wen Qin ◽  
Ji Ming Bian
Keyword(s):  
Electron Cyclotron Resonance ◽  
Diamond Films ◽  
Chemical Vapor ◽  
High Energy ◽  
Organic Chemical ◽  
High Quality ◽  
Small Surface ◽  
Force Microscopy ◽  
Atomic Force ◽  
Metal Organic

High quality GaN films are deposited on freestanding thick diamond films by electron cyclotron resonance plasma enhanced metal organic chemical vapor deposition (ECR-PEMOCVD). The characteristics of GaN films were investigated by x-ray diffraction analysis (XRD), reflection high energy electron diffraction (RHEED) and atomic force microscopy (AFM). The high quality GaN films with small surface roughness of 8.3 nm and high c-orientation are successfully achieved at the optimized nitriding time with the diamond substrate. These properties of GaN films with small surface smoothness and high c-orientation are well used as piezoelectric films for surface acoustic wave (SAW) devices.

Surface Reconstruction and Morphology of Hydrogen Sulfide Treated GaAs (001) Substrate

1996 ◽  
Vol 448 ◽  
Author(s):  
Jun Suda ◽  
Yoichi Kawakami ◽  
Shizuo Fujita ◽  
Shigeo Fujita
Keyword(s):  
Hydrogen Sulfide ◽  
Surface Reconstruction ◽  
Substrate Surface ◽  
High Vacuum ◽  
High Energy ◽  
Gaas Surface ◽  
Ex Situ ◽  
Force Microscopy ◽  
Atomic Force ◽  
Strained Quantum Well

AbstractWe report several new results in hydrogen sulfide (H2S) treatment of a GaAs (001) substrate. Surface reconstruction and morphology were investigated by in situ reflection high energy electron diffraction (RHEED) and ex situ atomic force microscopy (AFM) in terms of the annealing temperature and the H2S irradiation sequence. A (4 × 3) GaAs surface was obtained by annealing the substrate under H2S irradiation (4 × 10-7 Torr). The surface was atomically flat, i.e., large terraces with monolayer steps were clearly observed. A (2 × 6) S-terminated GaAs surface was obtained by irradiation H2S at 300°C on a Ga-terminated surface, which was formed by annealing at 580°C in high vacuum. The molecular beam epitaxy (MBE) growth of ZnSSe-based semiconductors on the (4 × 3) surface results in high quality structures such as a novel ZnSSe/ZnMgSSe tensile-strained quantum well (QW).

The Effects of Kcn Etching on Cu-Rich Epitaxial CuInSe2 Thin Films

1996 ◽  
Vol 426 ◽  
Author(s):  
P. Fons ◽  
S. Nikl ◽  
A. Yamada ◽  
M. Nishitanp ◽  
T. Wada ◽  
...  
Keyword(s):  
Thin Films ◽  
Surface Region ◽  
Etching Time ◽  
Cation Sublattice ◽  
Epitaxial Thin Films ◽  
Near Surface ◽  
Force Microscopy ◽  
Atomic Force ◽  
Before And After ◽  
Integrated Intensity

AbstractA series of Cu-rich CuInSe2 epitaxial thin films were grown by molecular beam epitaxy on GaAs(001) substrates from elemental sources at a growth temperature of 450 °C. All samples were grown with an excess of Cu. Electron microprobe analysis (EPMA) indicated a Cu/ In ratio of about 2.1–2.6 in the as-grown films. Additionally, the Se/ (In+Cu) ratio was observed to be ∼0.95 indicating that the films were slightly Se poor. These Cu-rich samples were etched in a KCN solution for periods ranging from 30 seconds to 3 minutes. EPMA measurements indicated that the bulk Cu/ In ratio was reduced to ∼0.92 in all films regardless of etching time. Atomic force microscopy (AFM) was used to characterize the topology of each sample before and after etching. These measurements indicated that the precipitates present on the as-grown films were removed and large nearly isotropic holes were etched into the sample to a depth of over 1000 Å even for etching times as short as 30 seconds. The samples were also evaluated both before and after etching using a Phillips MRD diffractometer with parallel beam optics and a 18,000 watt Cu rotating anode X-ray source in the chalcopyrite [001], [101], and [112] directions. A peak was observed at ∼15 degrees in the [001] scan after etching consistant with the presence of the ordered vacancy compound, CuIn3Se5. Additionally the integrated intensity ratios of the chalcopyrite (202) reflection to the chalcopyrite (101) reflection ∝(fCu-fIn)2 along the [101] direction indicated the presence of a near-surface region containing cation sublattice disorder that was subsequently removed by the etching process.

HOMO-EPITAXIAL GROWTH ON ZnO SUBSTRATE BY MO-CVD USING (C5H7O2)2

2007 ◽  
Vol 14 (04) ◽  
pp. 783-787 ◽  
Author(s):  
KOICH HAGA ◽  
TOETSU SHISHIDO ◽  
KAZUO NAKAJIMA ◽  
TAKAHIRO MATSUNAGA
Keyword(s):  
High Temperature ◽  
Photoelectron Spectroscopy ◽  
High Energy ◽  
Zno Films ◽  
High Temperature Annealing ◽  
High Quality ◽  
Ion Etching ◽  
Atomic Force ◽  
Good Crystallinity ◽  
Atomically Flat

High quality homo-epitaxial ZnO films were grown on Zn -terminated surfaces of ZnO (0001) single-crystal substrates with high-temperature annealing and Ar + ion etching. These films were prepared by low-pressure MO-CVD using zinc acetylacetonate ( C 5 H 7 O 2)2 and oxygen as source materials. High quality ZnO (0001) substrate was synthesized by the hydrothermal technique. The atomically flat surface without scratches was obtained by high temperature annealing at 800°C–1300°C in oxygen atmosphere. Ar + ion etching for the surface of ZnO substrates was critically important to the growth of ZnO films with good crystallinity. The epitaxial film and the ZnO substrate were characterized using reflection high-energy electron diffraction, atomic force microscope, and X-ray photoelectron spectroscopy.

scholarly journals Morphology and luminescence of photo-electrochemically synthesized porous silicon: Influence of varying current density

2017 ◽  
Vol 13 (4) ◽  
pp. 708-710
Author(s):  
Asad Thahe ◽  
Hazri Bakhtiar ◽  
Noriah Bidin ◽  
Zainuriah Hassan ◽  
Zainal Abidin Talib ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Current Density ◽  
Room Temperature ◽  
Gravimetric Method ◽  
Etching Time ◽  
Time Duration ◽  
High Quality ◽  
Force Microscopy ◽  
Room Temperature Photoluminescence ◽  
Atomic Force

Achieving high quality porous silicon (PSi) materials with desired porosity remains challenging. Three good qualities of PSi samples are prepared by Photo electro-chemically etching a piece of n-type Si inside the solution of 20 M HF, 10 M C2H5OH and 10 M H2O2 at fixed etching time duration (30 min) and varying current density (15 mA/cm2, 30 mA/cm2 and 45 mA/cm2). As-prepared sample morphologies are characterized via scanning electron microscopy (SEM) and atomic force microscopy (AFM). The gravimetric method is used to estimate the thickness and porosity of the prepared samples. Current density (etching time) dependent morphologies, electronic bandgap and room temperature photoluminescence (PL) properties of such PSi nanostructures are evaluated. These PSi structures revealed enhanced rectifying characteristics with increasing current density. 

Atmoic-Scale Control of Oxide Substrate Surface/Termination and Novel Heteroepitaxial Growth

1999 ◽  
Vol 587 ◽  
Author(s):  
Mamoru Yoshimoto ◽  
Keisuke Mizuno ◽  
Takafumi Miyahara
Keyword(s):  
Single Crystal ◽  
Sapphire Substrate ◽  
Substrate Surface ◽  
High Energy ◽  
Atomic Scale ◽  
The Novel ◽  
Heteroepitaxial Growth ◽  
Surface Termination ◽  
Oxide Substrates ◽  
Atomically Flat

AbstractAtomic-scale surface/termination of single-crystal oxide substrates were examined by coaxial impact collision ion scattering spectroscopy (CAICISS) and atomic force microscopy (AFM). CAICISS enabled us to determine the terminating atomic species and their arrangements of single crystal oxide substrates and epitaxial oxide films. Through thermal-annealing of the single crystal oxide substrates, atomically flat terrace and stepped structures were developed on the surface. The molecular layer-by-layer growth was verified by in situ monitoring of reflection high energy electron diffraction (RHEED) intensity oscillation. The atomic-scale substrate engineering made it possible to attain the novel heteroepitaxial growth such as step-decoration epitaxy resulting in the nanowire structures and diamond epitaxy on the ultrasmooth sapphire substrate. The diamond films could be grown epitaxially only on the atomically flat sapphire substrates by pulsed laser ablation of graphite. The novel application of the ultrasmooth sapphire substrate to the AFM observation stage for DNA molecules was also presented.

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