Observation Of Etch Pits Research Articles

Observation of Etch Pits of β-FeSi2 Single Crystals

We have observed etch pits of p-type β-FeSi2 single crystals grown by the temperature gradient solution growth method. Characteristic etch pits which depend on the surface orientation of the crystals were observed on the surface etched by diluted hydrofluoric acid and HF:HNO3:H2O=1:2:2–8 solutions. These etchants are suitable for the observation of etch pits and surface orientation of β-FeSi2 single crystals.

Tantalum diffusion barrier grown by inorganic plasma-promoted chemical vapor deposition: Performance in copper metallization

As-deposited and annealed tantalum films, grown by plasma-promoted chemical vapor deposition (PPCVD) using pentabromotantalum and hydrogen as coreactants, were evaluated as diffusion barriers in copper metallization. Stacks consisting of 500-nm-thick sputtered Cu/55-nm-thick untreated PPCVD Ta/Si were annealed in argon in the range 450 to 650 °C, in 50 °C intervals, along with sputtered Cu/preannealed PPCVD Ta/Si and sputtered Cu/sputtered Ta/Si stacks of identical thickness. Pre- and postannealed stacks were characterized by x-ray photoelectron spectroscopy, Auger electron spectroscopy, Rutherford backscattering spectrometry, hydrogen profiling, x-ray diffraction, atomic force microscopy, sheet resistance measurements, and Secco chemical treatment and etch-pit observation by scanning electron microscopy. The sputtered and preannealed PPCVD Ta films acted as viable diffusion barriers up to 550 °C, while the as-deposited PPCVD Ta films failed above 500 °C. In all cases, breakdown occurred through the migration of Cu into Si, rather than an interfacial reaction between Ta and Si, in agreement with previously reported results for sputtered Ta films. The accelerated barrier failure for as-deposited PPCVD Ta might have been caused by the presence of approximately 20 at.% hydrogen in the as-deposited PPCVD Ta, an observation which was supported by the enhanced performance of the same PPCVD Ta films after annealing-induced hydrogen removal.

Cross-Sectional Transmission Electron Microscopic Observation of Etch Hillocks and Etch Pits in LiTaO3 Single Crystal

Cross sections of etch hillocks and etch pits in LiTaO3 single crystal have been observed by transmission electron microscopy. The cross-sectional samples were prepared at their exact positions by the focused ion beam microfabrication method. Inverted polarized domains were observed both at the top of etch hillocks and at the bottom of etch pits, indicating that the etching figures originate in the inverted domain formed on the surface. Furthermore, some inverted domains that were pinned by lattice defects were also observed at the inner part of the crystal.

Observation of dislocation etch pits in epitaxial lateral overgrowth GaN by wet chemical etching

ABSTRACTThis work investigates dislocation etch pits in epitaxial lateral overgrowth (ELO) GaN by wet chemical etching. A mixture of H2SO4 and H3PO4 was used as a dislocation etchant, and SEM and AFM were employed to observe the surface topography. For the as-grown sample, SEM images present the flat, smooth surface without any pits or hillocks. After the chemical etching, hexagonal shaped etch pits were observed at the edge of ELO GaN. AFM observation of etched ELO GaN displayed high densities of etch pits clustered in the “window” region and the coalescent line of two growing fronts. In contrast, the overgrowth region was nearly free of etch pits. Moreover, we observed that different sizes of etch pits dominated in “window” region and coalescent region. This implied different types dislocations dominated in these regions.

Influences of Cu and Fe Impurities on Oxygen Precipitation in Czochralski-Grown Silicon

Characteristics of oxygen precipitation in Czochralski-grown silicon (CZ-Si) intentionally contaminated with Cu or Fe are investigated by means of Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), electron-beam-induced-current (EBIC) mapping and etch pit observation. It is found that oxygen precipitation is not influenced by the presence of Cu impurities, while it is enhanced significantly by the presence of Fe impurities even if the concentration of Fe is much lower than that of Cu. Precipitations of supersaturated Cu and O impurities are found to proceed independently of each other in Si crystals. Oxygen precipitates in an Fe-contaminated specimen are much denser and smaller than those in a noncontaminated specimen. Fe impurities seem to react with minute Si oxide particles which are present in as-grown CZ-Si crystals and reduce the nucleation barrier for oxygen precipitation.

Effect of Annealing of Titanium Nitride on the Diffusion Barrier Property in Cu Metallization

The diffusion barrier properties of 100 nm thick films, both as deposited and annealed, were investigated in the metallization system using sheet resistance measurements, etch pit observation, x‐ray diffractometry, and cross‐sectional transmission electron microscopy (XTEM). No reaction of the Cu with layer was observed up to 650°C for 1 h. However, by Secco etching of the Si surface, etch pits were first observed after annealing at 550°C for 1 h. XTEM analysis shows that the in‐diffusion of Cu results in the formation of dislocations in the Si substrate along the projection of Si {111} plane and precipitates (presumably Cu silicides) around the dislocation. Considerable densification of film was achieved by annealing at 450°C for 30 min in ambient. In system, it is shown that barrier properties are enhanced by annealing the prior to Al deposition. However, in Cu/annealed system, the postannealing temperature at which etch pits are first observed is still 550°C, and the size and density of etch pits are similar to the case of as‐deposited . Thus, we conclude that annealing of film does not enhance the diffusion barrier property of in system as it does in system.

Ion beam epitaxy of silicon films in an ultrahigh vacuum using a sputtering-type metal ion source

Ion beam epitaxy (IBE) of silicon films in an ultrahigh vacuum is carried out using a specially developed electric-mirror sputtering-type metal ion source. Silicon films with 2×1 reconstructed surface structures are homoepitaxially grown on silicon wafers above 320 °C, and contamination by oxygen and carbon is suppressed below the level of bulk Czochralski silicon (<1×1018 cm−3). Argon entrapment from sputtering discharge in the film is suppressed by controlling the ion energy during film growth, and metal contamination is suppressed below the detection limit (<1×1016 cm−3) of the conventional secondary ion mass spectroscopy system used. The IBE films exhibit bulklike perfect crystallinity, as examined by electron microscopy, etch-pit observation, Raman spectroscopy, and Rutherford backscattering spectroscopy. Precise and steep control of dopant profile is demonstrated in situ. Heavily doped (B:5×1018 cm−3, As: 1×1019 cm−3) silicon films are grown and the dopants are ideally activated in the films. These films exhibit bulklike carrier mobility.

Etch Pit Observation of GaP Grown on Si Substrate by Metalorganic Chemical Vapor Deposition

This paper describes the observation of the etch pits for GaP grown on Si substrate which correspond to dislocations. The etching solution is composed of HF and HNO3 at room temperature. The etch pits revealed by this solution correspond to those revealed by H3PO4 at 180°C.

Characterization of Antiphase Domain in GaP on Misoriented (001) Si Substrate Grown by Metalorganic Chemical Vapor Deposition

Antiphase domains (APD's) in GaP grown on (001) Si with different misorientation angles (0-6?) have been characterized by transmission electron microscopy (TEM) and etch pit observation. The self-annihilation of APD during growth is observed for GaP grown on exactly (001), 1?-off (001) and 2?-off (001) Si substrates, using TEM. A part of the APD is propagated to the surface in the case of exactly (001) and 1?-off (001) Si substrates. All the APD's are annihilated in the early stage of growth for GaP grown on 2?-off Si. On the other hand, no APD has been detected for GaP grown on 4?-off and 6?-off Si. The GaP surface morphology and the etch pit density are greatly affected by the APD's generated at the interface even if they are annihilated during the growth.

CdTe(111) growth on misoriented Si(100) substrates by hot-wall epitaxy

CdTe(111) layers were grown directly on misoriented Si(100) substrates by hot-wall epitaxy. The structure and crystallinity of the layer were examined by reflection high-energy electron diffraction (RHEED), etch-pit observation and X-ray diffraction measurements. The strain in the layer was investigated by X-ray Bond method. The layers on misoriented Si(100) substrates are composed of twinted domains elongated parallel to the misoriented direction of the substrates. A 5 μm thick layer was deformed by biaxial tensile stress by the difference between thermal expansion coefficients of CdTe and Si. The strain is relaxed as the layer thickness increases.

Homoepitaxial Chemical Vapor Deposition of 6H-SiC at Low Temperatures on {011̄4} Substrates

Homoepitaxial chemical vapor deposition of 6H-SiC at low temperatures on {011̄4} substrates has been investigated. The crystal growth was carried out using a SiH4-C3H8-H2 system in the temperature range of 1000∼1500°C. Crystallinity of grown layers was characterized by means of reflection high-energy electron diffraction and etch-pit observation. The influences of surface polarity and growth conditions on crystallinity of grown layers were investigated. Significant effects of C/Si ratio on the growth were observed. Homoepitaxial growth of 6H-SiC was realized on (01̄14̄)C-face substrates at temperatures as low as 1100°C, which is 700°C lower than that on {0001} basal planes.

Crystal growth of SiC by step-controlled epitaxy

Vapor phase epitaxial (VPE) growth of SiC on 6H-SiC substrates has been carried out at 1500°C. On well-oriented (0001)Si faces twin crystalline 3C-SiC was grown, whereas on off-oriented (0001)Si faces, single crystalline 6H-SiC was grown with a very smooth surface. This temperature is 300°C lower than that previously reported for 6H-SiC VPE growth. By the introduction of off-orientation, the density of surface steps is controlled. As a result, the growth on off-oriented substrates proceeds according to different mechanisms from that on well-oriented substrates. Surface morphology of grown layers on off-oriented substrates, however, varied with the off-direction. Grown layers are characterized by observation of etch-pits and photoluminescence (PL) measurements. The growth mechanism on (0001)Si faces of 6H-SiC is discussed on the basis of these experimental results.

Crystal growth and characterization of CdInGaS 4 and related compounds

Crystal growth of CdInGaS4 was performed by normal freezing and Bridgman methods. The characterization of the crystals was done along the growth direction by X-ray diffraction, optical absorption, photoluminescence, compositional analysis and etch pit observation. The physical properties investigated are essentially constant along the growth direction and independent of the method of crystal growth. The X-ray powder diffraction pattern of CdInGaS4 can roughly be reproduced by a computer simulation based on the structure deduced from that of ZnIn2S4. The crystal structure of Cd3InGaS6 was found to be a laminated structure composed of CdInGaS4 and Cds.

Antiphase Defect Reduction Mechanism in Mbe Grown Gaas on Si

ABSTRACTIt is shown that antiphase boundary (APB) is annihilated during the growth, by monitoring the surface with reflection high energy electron diffraction (RHEED). The RHEED observation indicates that double domain GaAs changes to single domain within a thickness of 100 nm, while the transition region is estimated to exist within 200 nm from GaAs-Si interface by scanning electron microscope (SEM) observation of etch pits on vicinally polished surface. The self-annihilation mechanism of APB is discussed from these results.

SEM analysis of weathered grains: Pretreatment effects

Research Article| May 01, 1987 SEM analysis of weathered grains: Pretreatment effects D. L. Cremeens; D. L. Cremeens 1Department of Agronomy, University of Illinois, Urbana, Illinois 61801 Search for other works by this author on: GSW Google Scholar R. G. Darmody; R. G. Darmody 1Department of Agronomy, University of Illinois, Urbana, Illinois 61801 Search for other works by this author on: GSW Google Scholar I. J. Jansen I. J. Jansen 1Department of Agronomy, University of Illinois, Urbana, Illinois 61801 Search for other works by this author on: GSW Google Scholar Author and Article Information D. L. Cremeens 1Department of Agronomy, University of Illinois, Urbana, Illinois 61801 R. G. Darmody 1Department of Agronomy, University of Illinois, Urbana, Illinois 61801 I. J. Jansen 1Department of Agronomy, University of Illinois, Urbana, Illinois 61801 Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1987) 15 (5): 401–404. https://doi.org/10.1130/0091-7613(1987)15<401:SAOWGP>2.0.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation D. L. Cremeens, R. G. Darmody, I. J. Jansen; SEM analysis of weathered grains: Pretreatment effects. Geology 1987;; 15 (5): 401–404. doi: https://doi.org/10.1130/0091-7613(1987)15<401:SAOWGP>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Fresh microcline, albite, and almandine, along with soil grains, were treated with various traditional pretreatments prior to observation with scanning electron microscopy (SEM). The grains were observed with SEM and given ratings for each of several surface properties to determine which pretreatments produced clean surfaces on soil grains without laboratory-induced damage on the fresh mineral grains.Gentle overnight shaking in 2% sodium bicarbonate at pH 9.5 produced the most effective cleaning of soil grains with the least amount of induced damage to fresh mineral samples. This pretreatment was equivalent to that given the control samples (shaken overnight in distilled water) for observations of etch pits on fresh mineral samples within a 25% equivalence (or negligible difference) interval. Ultrasonification, hydrogen peroxide, and boiling hydrochloric acid caused the most damage to mineral samples, mainly in the form of 0.5-µm etch pits. Boiling hydrochloric acid, boiling nitric acid, and stannous chloride resulted in increased coated surfaces on soil grains. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Si surface study after Ar ion-assisted Cl2 etching

Silicon surfaces after Ar ion-assisted etching in Cl2 gas atmosphere were studied for various Ar ion current densities and Cl2 gas pressures. The number of incident Ar ions was varied in 6×1014–3×1016 ions/cm2/s while the number of incident Cl2 molecules was varied in 0–3×1017 molecules/cm2/s. Ar ion acceleration energy was fixed at 1 keV. High etching rate, about 5000 Å/min, was observed with a high incident rate of both Ar ions and Cl2 molecules. On the other hand, high etch yield was observed at low incident rate of Ar ions and high incident rate of Cl2 molecules. The amount of surface defects and surface chemical adsorption states, which vary with different etching conditions, were studied by etch pit observation after thermal oxidation followed by Secco-etching, x-ray photoelectron spectroscopy (XPS), and reflection high energy electron diffraction (RHEED). Silicon surfaces, etched under high etch yield etching conditions, showed relatively high Si2O3 existence by XPS measurement, and high density etch pits. It is considered to be related with high density surface defects and roughness. Etch pits did not appear after conventional wet cleaning process. It is caused by a little surface oxidation and relatively less Si2O3 existence than other kinds of oxides on the surface.

Surface Defects on MBE-Grown GaAs

The most common macroscopic defects in GaAs layers grown by MBE, i.e. oval defects, were studied. TEM observation shows that oval defects include stacking faults and that the crystalline quality is considerably inferior around these stacking faults. The successive optical microscopic observation of step-etched surfaces reveals that for an epitaxial layer with an oval defect density of more than 104/cm2, the majority of the oval defects originate in the epitaxial layer, while for an epitaxial layer with an oval defect density of less than 103/cm2, they originate at the interface between the epitaxial layer and the substrate. X-ray topography and observation of the dislocation etch pits clearly show that substrate dislocations are not responsible for the oval defects.

Plastic deformation and dislocation structure of single crystal mercuric iodide

A systematic investigation of plasticity in single crystal mercuric iodide was carried out. Over eighty compression tests were performed on single crystal specimens oriented variously with respect to the axis of loading. Three characteristic loading responses were observed and classified according to crystal orientation, as follows: (a) the direction of load was perpendicular to the [001] axis, (b) the loading direction was parallel to [001] and (c) the load was neither parallel nor perpendicular to [001]. In cases a and b, under sufficient load, the samples always exhibited brittle failure (without prior plastic deformation) whereas, in case c, the samples were always easily plastically deformed by slip of (001) planes. The case c plastic deformation also exhibited work hardening. A dislocation model for plasticity in mercuric iodide is induced from the experimental results. The model consists of “easy glide” dislocations, the cores of which are parallel to (001) planes, and “hard glide” dislocations that intersect the (001) planes. Movement of the easy glide dislocations causes the (001) slip in case c, whereas interactions between the easy and hard glide dislocations account for the work hardening. The results of other experiments (including creep, annealing, microscopic observation of dislocation etch pits, and bending) are consistent with the model. Deformation during large angle bending tests is a particularly remarkable phenomenon.

Birefringence and structural defects in Cu2O crystals

We have investigated the birefringence in Cu2O crystals which is induced by internal stress. The observed birefringence near precipitations, called ‘‘teratoides,’’ in as-grown crystals is shown to be related to pile-ups formed in (100) planes. This interpretation is supported by the direct observation of etch pits in the birefringent regions near teratoides and by the observation of the same birefringence in other pile-ups that are not related to teratoides. The analysis of the birefringence using a quarter-wave plate shows that the slow principal axis in the crystal is parallel to Burgers vector of dislocations in pile-ups. Comparison of the birefringence observed in plastically deformed crystals with that near pile-ups in as-grown crystals, indicates the formation of pile-ups by plastic deformation. The pile-ups in this case are perpendicular to the branches of cross shaped birefringent regions. This result is in agreement with the prediction of the excitonic photoconductivity measurements.

REDUCTION OF DISLOCATIONS IN LPE LAYERS DUE TO THE ACTION OF THERMAL STRESSES

We present here a model of the reduction of dislocations in LPB layers by the formation of oriented interfacial dislocations parallel to the surface of the substrate due to the glide motion of substrate threading dislocations which is drived by the thermal stress produced by a temperature difference. In the temprature gradient LPE under a steady natural convection flow, there is a temperature difference across the thickness of the substrte. The temperature difference can cause a thermal shear stress in the fixed substrate. Thick GaAs and Ga1-xAlxAs (x oriented dark line defects. The observation of subface etch pits shows that the epitaxial layers have lower dislocation densities than that of the substrates or are even dislocation-free. The observations of interfacial etch grooves and cathodoluminescence show that substrate threading dislocations bent so that segments run along the interface and a interfacial dislocation network is formed. The transmission electron microscopy observation shows that the majority of these interfacial dislocations are 60° type dislocations and the minority are Lomer dislocations. It implies that it is possible to eliminate all substrate threading dislocations with the introduction of interfacial dislocations by thermal shear stress.