Effect of Substrate Orientation on the Growth Rate and Surface Morphology on GaSb Grown by Metal-Organic Vapor Phase Epitaxy

2005 ◽  
Vol 864 ◽  
Author(s):  
Jian Yu ◽  
Ishwara B. Bhat
Keyword(s):  
Growth Rate ◽  
Surface Morphology ◽  
Hexagonal Structure ◽  
Spiral Growth ◽  
Type I ◽  
Type Ii ◽  
Substrate Orientation ◽  
Metal Organic ◽  
Growth Features ◽  
Step Flow Growth

AbstractMOVPE of GaSb grown on (100), (111)A and (111)B GaSb substrates were investigated to study the effect of substrate orientation on the growth rate and surface morphology. Besides growth temperature and V/III ratio, the GaSb growth rate strongly depends on the crystallographic orientation. As the V/III ratio rises, the growth rate on the (111)B oriented substrate decreases, whereas that on the (111)A oriented substrate increases. The surface morphology on different substrates was studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM). On (111)A substrates, triangular hillocks are the dominant defects, while on (111)B planes, three distinct types of hexagonal hillocks are observed, namely, non-flat top hexagonal structure with spiral growth features (Type I), flat top structure with lateral growth features (Type II), and non-flat top hexagonal structure with multiple islands (Type III). For all types, the basal edges of each hillock are preferentially aligned along <110> directions. A closer look reveals that the top surface of Type II feature consists of many levels of small hexagonal shaped terraces, with each step height in the monolayer range, indicating a step flow growth involved.

Nanoscale Metal–Organic Frameworks Stabilize Bacteriochlorins for Type I and Type II Photodynamic Therapy

2020 ◽  
Vol 142 (16) ◽  
pp. 7334-7339 ◽  
Author(s):  
Taokun Luo ◽  
Kaiyuan Ni ◽  
August Culbert ◽  
Guangxu Lan ◽  
Zhe Li ◽  
...  
Keyword(s):  
Photodynamic Therapy ◽  
Metal Organic Frameworks ◽  
Type I ◽  
Type Ii ◽  
Metal Organic

Growth Mechanisms and Surface Morphology of Ybco Based High-Tc Thin Films and Heterostructures for sns Junctions

1999 ◽  
Vol 574 ◽  
Author(s):  
R. A. Rao ◽  
C. B. Eom
Keyword(s):  
Thin Films ◽  
Surface Morphology ◽  
Spiral Growth ◽  
High Tc ◽  
Ybco Films ◽  
Step Flow ◽  
Pseudomorphic Growth ◽  
Growth Features ◽  
High Degree ◽  
Miscut Angle

AbstractWe have controlled the nanoscale growth mechanism and surface morphology of YBa2Cu3O7 (YBCO) based high-Tc thin films and heterostructures, using miscut SrTiO3 substrates. On exact (001) SrTiO3 substrates, the YBCO films grow in a screw dislocation growth mode. The barrier layers (La6.4Sr1.6Cu8O20 and PrBa2Cu3O7) grown on top of such a YBCO film also show spiral growth features, indicating pseudomorphic growth. On miscut substrates (with miscut angle ≥ 4° toward [010]) the YBCO films grow by step-flow. However, the La6.4Sr1. 6Cu8O20 layers grown on such YBCO bottom electrodes, show a high degree of step bunching with rough surface. In contrast, the PrBa2Cu3O7 layers show clear step-terrace surface morphology similar to the underlying YBCO bottom electrode, suggesting the existence of periodic nanoscale steps at the S-N interface. These heterostructures can be used for the fabrication of SNS Josephson junctions to take advantage of the proximity effect coupling at the nanoscale steps at the interface.

Adaptive Modifications in Four Fish Species of the GenusGarra(Teleostei; Cyprinidae) in Basistha River, Assam, India

2018 ◽  
Vol 24 (3) ◽  
pp. 310-317
Author(s):  
Jafrin F. Hussain ◽  
Sabitry Bordoloi
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Surface Morphology ◽  
Fish Species ◽  
Taste Buds ◽  
Stream Fish ◽  
Type I ◽  
Type Ii ◽  
Guwahati City ◽  
Scanning Electron

AbstractThis paper deals with the study of the surface morphology of barbels, upper lips, and adhesive discs in four hill stream fish species collected from Basistha River, a torrential river in Guwahati city, Assam, India. The four species belonging to the genusGarranamely,Garra gotyla(Gray, 1830),Garra gravelyi(Annandale, 1919),Garra stenorhynchus(Jerdon, 1849), andGarra nasuta(McClelland, 1838) were collected from the same torrential habitat. These fish revealed anatomical peculiarities in their barbels, lips, and adhesive discs which are believed to help them in adapting to such habitats. Organs exhibiting adaptive modifications (barbels, lips, and adhesive discs) were studied with the scanning electron microscope. The study primarily revealed the presence of type I and type II taste buds in the barbels, lips, and adhesive discs, and numerous unculi surrounded by microridges in the upper lips and adhesive discs. A cumulative, intercalated action of these organs enables these fish to adhere and adapt to rocky, torrential streams. Special ability to adapt to these habitats was reflected from the two types of taste buds (I and II) present in the barbels, and the clustering of excrescencies bearing unculi in the lips and adhesive discs of the fish.

Homoepitaxial Growth of 4H-SiC Using CH3Cl Carbon Precursor

2005 ◽  
Vol 483-485 ◽  
pp. 81-84 ◽  
Author(s):  
Yaroslav Koshka ◽  
Huang De Lin ◽  
Galyna Melnychuck ◽  
Michael S. Mazzola ◽  
Jeffery L. Wyatt
Keyword(s):  
Growth Rate ◽  
Surface Morphology ◽  
Epitaxial Growth ◽  
Carbon Precursor ◽  
Lower Growth ◽  
Good Surface ◽  
Growth System ◽  
Phase Precursor ◽  
Lower Growth Rate ◽  
Step Flow Growth

The results of the initial experiments with halogenated carbon precursor chloromethane (CH3Cl) for epitaxial growth of 4H-SiC are presented. The growth rate for mirror-like morphology was easily increased up to about 7 µm/hr at C-rich conditions without detectable surface morphology degradation. Further increase of the silane flow resulted in island formation. The growth with the traditional silane-propane system at the same conditions (and optimized Si/C ratio) produced a very different result, with the growth rate decreasing from upstream to downstream, and morphology degradation taking place for much lower growth rate than in CH3Cl growth. Consequently, the epitaxial growth with chloromethane appears to have significantly different kinetics of the gas-phase precursor decomposition and different mechanisms of the surface reactions, which favors the step-flow growth. In addition, these preliminary data indicated that the maximum achievable growth rate corresponding to the good surface morphology may be noticeably larger for the CH3Cl+SiH4+H2 growth system.

Cathodeluminescence Characterization of AlGaN Film Grown by MOCVD

2010 ◽  
Vol 143-144 ◽  
pp. 966-970
Author(s):  
Lian Jia Wang ◽  
You Zhang Zhu ◽  
Hong Xia Wang ◽  
Ben Li Liu ◽  
Jin She Yuan
Keyword(s):  
Surface Morphology ◽  
Defect Density ◽  
Chemical Vapor ◽  
Hexagonal Structure ◽  
Single Atom ◽  
Luminescence Properties ◽  
Organic Chemical ◽  
Good Surface ◽  
Photo Detectors ◽  
Metal Organic

Recent achievements in III-nitride semiconductor structures growth have allowed ultraviolet (UV) photo-detectors based on these compounds to be well established today. In this article, AlGaN film of 1-μm thickness was grown on Al2O3 substrate by metal-organic chemical vapor deposition (MOCVD). The AFM was used to analyze the surface morphology of the AlGaN film; X-ray diffraction measurements were used to study the quality of the film’ crystal structure; Cathode-ray luminescence(CL) was employed to study the luminescence properties of the AlGaN film. The result shows that there is a single atom layer on the AlGaN film’surface, and it shows that a low-defect-density AlGaN film with good surface morphology and single crystal Hexagonal structure has been obtained. It is found that there is some relationship between the film’crystal structure , dislocations and the luminescence properties . PACS: 73.61.

scholarly journals Intrinsic nucleus-targeted ultra-small metal–organic framework for the type I sonodynamic treatment of orthotopic pancreatic carcinoma

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Tao Zhang ◽  
Yu Sun ◽  
Jing Cao ◽  
Jiali Luo ◽  
Jing Wang ◽  
...  
Keyword(s):  
Pancreatic Carcinoma ◽  
Metal Organic Framework ◽  
Phase Cell ◽  
Great Promise ◽  
Type I ◽  
Type Ii ◽  
Independent Manner ◽  
Low Intensity ◽  
Metal Organic ◽  
Organic Framework

Abstract Background Sonodynamic therapy (SDT) strategies exhibit a high tissue penetration depth and can achieve therapeutic efficacy by facilitating the intertumoral release of reactive oxygen species (ROS) with a short lifespan and limited diffusion capabilities. The majority of SDT systems developed to date are of the highly O2-dependent type II variety, limiting their therapeutic utility in pancreatic cancer and other hypoxic solid tumor types. Results Herein, a nucleus-targeted ultra-small Ti-tetrakis(4-carboxyphenyl)porphyrin (TCPP) metal–organic framework (MOF) platform was synthesized and shown to be an effective mediator of SDT. This MOF was capable of generating large quantities of ROS in an oxygen-independent manner in response to low-intensity ultrasound (US) irradiation (0.5 W cm−2), thereby facilitating both type I and type II SDT. This approach thus holds great promise for the treatment of highly hypoxic orthotopic pancreatic carcinoma solid tumors. This Ti-TCPP MOF was able to induce in vitro cellular apoptosis by directly destroying DNA and inducing S phase cell cycle arrest following US irradiation. The prolonged circulation, high intratumoral accumulation, and nucleus-targeting attributes of these MOF preparations significantly also served to significantly inhibit orthotopic pancreatic tumor growth and prolong the survival of tumor-bearing mice following Ti-TCPP + US treatment. Moreover, this Ti-TCPP MOF was almost completely cleared from mice within 7 days of treatment, and no apparent treatment-associated toxicity was observed. Conclusion The nucleus-targeted ultra-small Ti-TCPP MOF developed herein represents an effective approach to the enhanced SDT treatment of tumors in response to low-intensity US irradiation. Graphic abstract

Heat-Etching with a Bullivant Type II Simple Freeze-Cleave Device

1970 ◽  
Vol 28 ◽  
pp. 106-107 ◽  
Author(s):  
Ronald S. Weinstein ◽  
N. Scott McNutt
Keyword(s):  
New Zealand ◽  
General Hospital ◽  
Massachusetts General Hospital ◽  
Type I ◽  
Type Ii ◽  
Collaborative Effort ◽  
Temperature And Pressure ◽  
The University

The Type I simple cold block device was described by Bullivant and Ames in 1966 and represented the product of the first successful effort to simplify the equipment required to do sophisticated freeze-cleave techniques. Bullivant, Weinstein and Someda described the Type II device which is a modification of the Type I device and was developed as a collaborative effort at the Massachusetts General Hospital and the University of Auckland, New Zealand. The modifications reduced specimen contamination and provided controlled specimen warming for heat-etching of fracture faces. We have now tested the Mass. General Hospital version of the Type II device (called the “Type II-MGH device”) on a wide variety of biological specimens and have established temperature and pressure curves for routine heat-etching with the device.

Labelling of non-A, non-B hepatitis infected chimpanzee hepatocytes with nuclease-gold conjugates

1984 ◽  
Vol 42 ◽  
pp. 250-251
Author(s):  
G. D. Gagne ◽  
M. F. Miller ◽  
D. A. Peterson
Keyword(s):  
Endoplasmic Reticulum ◽  
Experimental Infection ◽  
Uranyl Acetate ◽  
Type I ◽  
Cellular Injury ◽  
Type Ii ◽  
Tubular Structures ◽  
Type Iii ◽  
Type Iv ◽  
Infected Chimpanzee

Experimental infection of chimpanzees with non-A, non-B hepatitis (NANB) or with delta agent hepatitis results in the appearance of characteristic cytoplasmic alterations in the hepatocytes. These alterations include spongelike inclusions (Type I), attached convoluted membranes (Type II), tubular structures (Type III), and microtubular aggregates (Type IV) (Fig. 1). Type I, II and III structures are, by association, believed to be derived from endoplasmic reticulum and may be morphogenetically related. Type IV structures are generally observed free in the cytoplasm but sometimes in the vicinity of type III structures. It is not known whether these structures are somehow involved in the replication and/or assembly of the putative NANB virus or whether they are simply nonspecific responses to cellular injury. When treated with uranyl acetate, type I, II and III structures stain intensely as if they might contain nucleic acids. If these structures do correspond to intermediates in the replication of a virus, one might expect them to contain DNA or RNA and the present study was undertaken to explore this possibility.

Comparative surface and ultrastructural views of methylotrophic bacteria by TEM, STEM, SE, and freeze-etch electron microscopy.

1987 ◽  
Vol 45 ◽  
pp. 792-793
Author(s):  
T.A. Fassel ◽  
M.J. Schaller ◽  
M.E. Lidstrom ◽  
C.C. Remsen
Keyword(s):  
Cytoplasmic Membrane ◽  
Structural Features ◽  
Methylotrophic Bacteria ◽  
Type I ◽  
Type Ii ◽  
Membrane Complex ◽  
Oxidation Of Methane ◽  
Methane Oxidizing Bacteria ◽  
Wall Structures ◽  
Methylomonas Albus

Methylotrophic bacteria play an Important role in the environment in the oxidation of methane and methanol. Extensive intracytoplasmic membranes (ICM) have been associated with the oxidation processes in methylotrophs and chemolithotrophic bacteria. Classification on the basis of ICM arrangement distinguishes 2 types of methylotrophs. Bundles or vesicular stacks of ICM located away from the cytoplasmic membrane and extending into the cytoplasm are present in Type I methylotrophs. In Type II methylotrophs, the ICM form pairs of peripheral membranes located parallel to the cytoplasmic membrane. Complex cell wall structures of tightly packed cup-shaped subunits have been described in strains of marine and freshwater phototrophic sulfur bacteria and several strains of methane oxidizing bacteria. We examined the ultrastructure of the methylotrophs with particular view of the ICM and surface structural features, between representatives of the Type I Methylomonas albus (BG8), and Type II Methylosinus trichosporium (OB-36).

Sign in / Sign up

Export Citation Format

Share Document