Pulsed Excimer Laser Ablation Deposition of Boron Nitride on Si (100) Substrates

1992 ◽  
Vol 242 ◽  
Author(s):  
T. A. Friedmann ◽  
K. F. McCarty ◽  
E. J. Klaus ◽  
D. Boehme ◽  
W. M. Clift ◽  
...  
Keyword(s):  
Boron Nitride ◽  
Excimer Laser ◽  
Laser Energy ◽  
Cubic Phase ◽  
High Concentration ◽  
Force Microscopy ◽  
Ir Reflection ◽  
Transmission Electron ◽  
Ir Transmission ◽  
Background Gas

ABSTRACTWe are studying the boron nitride system by using a pulsed excimer laser to ablate from hexagonal BN (hBN) targets to form cubic BN (cBN) films. We are depositing BN films on heated (600°C) silicon (100) surfaces in a flowing (0- 10 sccm) ambient background gas of either NH3 or N2 of varying partial pressure (0–100 m Torr). Infrared (IR) reflection spectroscopy indicates the films have short-range hexagonal order. Some films grown at low laser energy densities have shown the cubic phase in IR transmission. Auger electron spectroscopy (AES) indicates the films are nitrogen deficient, which is linked to changes in the target stoichiometry with increasing laser fluence. Raman spectroscopy on the films shows only a strong background luminescence suggesting a high concentration of defects associated with the nitrogen vacancies. Atomic force microscopy (AFM) of the films shows a surface morphology that roughens as the growth rate increases. In order to improve the film stoichiometry it was necessary to actively enhance the nitrogen content of the films. It was found that bombarding films during growth with ions from an ion gun filled with NH3 gas increased the N/B ratio but did not enhance the cubic phase. RF biasing the substrate gave films which showed both cubic and hexagonal features in IR reflection. High resolution transmission electron microscopy (TEM) confirms the presence of cBN grains of ∼ 200Å size in films grown with an RF bias.

scholarly journals Синтез и оптические свойства пленок оксида титана, модифицированных кобальтом

2019 ◽  
Vol 126 (6) ◽  
pp. 751
Author(s):  
В.А. Логачева ◽  
А.Н. Лукин ◽  
Н.Н. Афонин ◽  
О.В. Сербин
Keyword(s):  
Magnetic Force ◽  
Optical Band Gap ◽  
Incident Angle ◽  
Cubic Phase ◽  
Titanium Oxides ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Ir Reflection ◽  
Ir Reflection Spectra

Using X-ray phase analysis, scanning electron microscopy atomic force and magnetic force microscopy, and IR spectroscopy the properties of polycrystalline TiO2 films modified by cobalt during magnetron sputtering and subsequent pulsed photon processing in air have been investigated. It has been found that in the course of the modification, a nanocrystalline (with a grain size of ~ 50 nm) film consisting of cobalt and titanium oxides is formed. Their surface exhibits magnetic properties. In the IR reflection spectra obtained at different incident angle of beam, two of the transverse optical (TO) phonons and their corresponding longitudinal (LO) phonons above 500–600 cm–1 were observed, which identify the formation of Co3O4 in the spinel structure. The study of optical absorption indicates the predominant existence in the films of phases with direct optical transitions. The optical band gap value was 1.43 and 1. 83 eV for Co3O4 and 2.65 eV for the cubic phase of CoO.

Quantum Confinement of Above-Band-Gap Transitions in Ge Quantum Dots

1999 ◽  
Vol 588 ◽  
Author(s):  
C. W. Teng ◽  
J. F. Muth ◽  
R. M. Kolbas ◽  
K. M. Hassan ◽  
A. K. Sharma ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Band Gap ◽  
Quantum Confinement ◽  
Laser Energy ◽  
Present Report ◽  
State Transitions ◽  
Force Microscopy ◽  
Transmission Electron ◽  
Ge Quantum Dots ◽  
Germanium Quantum Dots

AbstractA number of research efforts have been focused on self-assembled germanium quantum dots in which indirect optical transitions take place across the band gap. However, many questions regarding the confined electronic state transitions of Ge quantum dots still remain unanswered. In the present report, we have deposited ten alternating layers of crystalline Ge quantum dots embedded in an Al2O3 or an AIN matrix on sapphire substrates by pulsed laser deposition. The average dot sizes (73 Å to 260 Å) were controlled by the laser energy density, deposition time and substrate temperature. The spectral positions of both the E1 and the E2 transitions in the absorption spectra at room temperature and 77 K shift toward higher energy (ΔE1=1.19 eV, ΔE2 =0.57 eV) as the Ge dot size decreases (73 Å). Structural analysis using transmission electron microscopy and atomic force microscopy and the interpretation of optical absorption measurements in terms of quantum confinement of carriers in both transitions are presented.

CHARACTERIZATION OF CUBIC BORON NITRIDE THIN FILMS DEPOSITED BY RF SPUTTER

2002 ◽  
Vol 16 (28n29) ◽  
pp. 4339-4342 ◽  
Author(s):  
JINXIANG DENG ◽  
GUANGHUA CHEN ◽  
XUEMEI SONG
Keyword(s):  
Thin Films ◽  
Boron Nitride ◽  
Photoelectron Spectroscopy ◽  
Hexagonal Boron Nitride ◽  
Cubic Boron Nitride ◽  
Cubic Phase ◽  
Force Microscopy ◽  
Si Substrates ◽  
Atomic Force ◽  
Fourier Transformation Infrared Spectroscopy

Cubic boron nitride (c-BN) thin films have been deposited on Si substrates by radio frequency sputter. Sputtering target was hot pressed hexagonal boron nitride of 4N purity. Sputtering gas was the mixture of nitrogen and argon. During depositing c-BN thin films, substrates were biased by dc voltage negatively with respect to ground. By optimizing the deposition conditions, the boron nitride (BN) films containing a large amount of cubic phase were obtained. The samples were characterized with Fourier transformation infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). According to FTIR, the cubic phase content of c-BN thin films was evaluated to be 92. The B/N ratio was estimated to be approximately 1 from XPS. The AFM shows that the c-BN thin films delaminated from Si substrates obviously.

scholarly journals Advanced Ga2O3/Lignin and ZrO2/Lignin Hybrid Microplatforms for Glucose Oxidase Immobilization: Evaluation of Biosensing Properties by Catalytic Glucose Oxidation

Catalysts ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1044
Author(s):  
Artur Jędrzak ◽  
Tomasz Rębiś ◽  
Maria Kuznowicz ◽  
Agnieszka Kołodziejczak-Radzimska ◽  
Jakub Zdarta ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Glucose Oxidase ◽  
Glucose Biosensor ◽  
Carbon Paste ◽  
Electrochemical Tests ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Biosensor System ◽  
Ir Transmission

In this study, novel Ga2O3/lignin and ZrO2/lignin hybrid materials were obtained and used as supports for the adsorption of the enzyme glucose oxidase (GOx). A biosensor system based on the hybrid supports was then designed to determine the concentration of glucose in various solutions. The obtained bioinspired platforms were analyzed to determine chemical and physical properties of the support structures. A determination was made of the effectiveness of the proposed method of immobilization and the quality of operation of the constructed glucose biosensor in electrochemical tests. To characterize the materials, Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), electrokinetic (zeta) potential measurements, atomic force microscopy (AFM), particle size measurements (NIBS technique), and elemental analysis (EA) were used. In further research, glucose oxidase (GOx) was immobilized on the surface of the obtained functional Ga2O3/lignin and ZrO2/lignin biomaterials. The best immobilization capacities—24.7 and 27.1 mg g−1 for Ga2O3/lignin and ZrO2/lignin, respectively—were achieved after a 24 h immobilization process. The Ga2O3/Lig/GOx and ZrO2/Lig/GOx systems were used for the construction of electrochemical biosensor systems, in a dedicated carbon paste electrode (CPE) with the addition of graphite and ferrocene.

Characterization of (Bi0.25Sb0.75)2Te3 Deposited by Pulsed Laser Deposition

2008 ◽  
Author(s):  
Ahmed Kamal ◽  
Hassan Abu Bakr ◽  
Ziyang Wang ◽  
H. El Samman ◽  
Paolo Fiorini ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Pulsed Laser Deposition ◽  
Laser Annealing ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Background Gas

The main objective of this work is to investigate the possibility of preparing bismuth telluride thin films using pulsed laser deposition. The effect of varying the deposition pressure, laser fluence, and the deposition temperature on the surface roughness, film composition, grain microstructure and electrical resistivity is analyzed using, scanning electron microscopy, atomic force microscopy, X-ray fluorescence, transmission electron microscopy, and four point probe measurements. It is demonstrated that relatively smooth films can be deposited at a laser flounce of 0.6 J/cm2 and using argon as a background gas at 10−1 mbar. On the other hand, resistivities as low as 2 mΩ.cm can be obtained by either depositing the film at 200°C, or by post-laser annealing films deposited at room temperature.

Transmission Electron Microscopy of Excimer Laser Crystallized Amorphous Si Thin Films

1990 ◽  
Vol 192 ◽  
Author(s):  
G. B. Anderson ◽  
R. Z. Bachrach ◽  
K. Winer ◽  
J. B. Boyce ◽  
F. A. Ponce ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Excimer Laser ◽  
Defect Density ◽  
Laser Energy ◽  
Laser Crystallization ◽  
Transmission Electron ◽  
High Resolution Tem ◽  
Stratified Structure

ABSTRACTThe results of a transmission electron microscopy (TEM) study of excimer laser crystallized a-Si:H thin films are described in this paper. High resolution TEM has shown the crystallization threshold of 10−2 P a-Si:H, grown by PECVD, to be 85 mj/cm2. TEM reveals that PECVD a-Si:H films crystallize in a stratified structure at laser energy densities greater than 120 mj/cm2. This stratified structure consists of a polycrystalline Si region near the surface, a microcrystalline region below the polycrystalline region and uncrystallized a-Si near the substrate. The depth of the crystallized region increases as the laser energy density increases. Spherical voids are also present in the film in the microcrystalline region. These voids are formed by H2 evolving from the film during crystallization. TEM also reveals that thermal annealing a 50 nm film of a-Si:H followed by laser crystallization produces 100 nm Si grains with low defect density.

Growth Mechanism and Opmization of MOD CeO2 Buffer Layers for TFA YBa2Cu3O7/CeO2 Multilayers

2005 ◽  
Vol 868 ◽  
Author(s):  
Felip Sandiumenge ◽  
Andrea Cavallaro ◽  
Mariona Coll ◽  
Jaume Gàzquez ◽  
Teresa Puig ◽  
...  
Keyword(s):  
Grain Growth ◽  
High Energy ◽  
Buffer Layers ◽  
Atmospheric Conditions ◽  
X Ray Diffraction ◽  
High Concentration ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Granular Microstructure

AbstractThe evolution from a partially oriented granular microstructure to a dense epitaxial one in CeO2 buffer layers deposited by metallorganic decomposition (MOD) on single crystal Y-stabilised ZrO2 (YSZ) substrates, has been investigated. CeO2 buffer layers were investigated using X-ray diffraction (XRD), atomic force microscopy (AFM), reflection high energy electron diffraction (RHEED), transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS). Reducing atmospheric conditions inhibit grain growth resulting in a nanometric granular microstructure with a high concentration of C impurities decorating grain boundaries and porosity. Oxidation and elimination of C species promotes grain growth resulting in a dense epitaxial film, as well as stabilizes otherwise energetically prohibitive polar (001) planes. Trifluoracetate (TFA) derived MOD YBa2Cu3O7 (YBCO) films deposited on optimized CeO2 buffers exhibit a sharp interface while the undesired reaction giving BaCeO3 is minimized. Jc values of 1.5 MA/cm2 and 14 MA/cm2 at 77K and 5K, respectively, are achieved.

Ion-Assisted Pulsed Laser Deposition of Cubic Boron Nitride on Si (100) Substrates

1992 ◽  
Vol 285 ◽  
Author(s):  
T. A. Friedmann ◽  
K. F. Mccarty ◽  
E. J. Klaus ◽  
H. A. Johnsen ◽  
D. L. Medlin ◽  
...  
Keyword(s):  
Boron Nitride ◽  
Cubic Boron Nitride ◽  
Ion Source ◽  
Laser Deposition ◽  
Reflection Spectroscopy ◽  
Grain Sizes ◽  
Broad Beam ◽  
Selected Area Electron Diffraction ◽  
Ir Reflection ◽  
Transmission Electron

ABSTRACTWe are studying the boron nitride system by using a pulsed excimer laser to ablate from hexagonal BN (hBN) targets to form cubic BN (cBN) films. We are depositing BN films on heated (400°C) Si (100) surfaces and are using a broad beam ion source operated with Ar and N2 source gasses to produce BN films with a high percentage of sp3-bonded cBN. The best films to date show ∼85% sp3-bonded BN as determined from infrared (IR) reflection spectroscopy. High resolution transmission electron microscopy (TEM) and selected area electron diffraction (SAD) confirm the presence of cBN in these samples. The films are polycrystalline and show grain sizes up to 500 Å.

Scanning tunneling microscopy and atomic force microscopy: New tools for biology

1989 ◽  
Vol 47 ◽  
pp. 778-779
Author(s):  
CE Bracker ◽  
P. K. Hansma
Keyword(s):  
Physical Property ◽  
Scanning Probe ◽  
Scanning Tunneling ◽  
Small Scale ◽  
Tunneling Microscopy ◽  
Force Microscopy ◽  
New Family ◽  
Small Probe ◽  
Atomic Force ◽  
Transmission Electron

A new family of scanning probe microscopes has emerged that is opening new horizons for investigating the fine structure of matter. The earliest and best known of these instruments is the scanning tunneling microscope (STM). First published in 1982, the STM earned the 1986 Nobel Prize in Physics for two of its inventors, G. Binnig and H. Rohrer. They shared the prize with E. Ruska for his work that had led to the development of the transmission electron microscope half a century earlier. It seems appropriate that the award embodied this particular blend of the old and the new because it demonstrated to the world a long overdue respect for the enormous contributions electron microscopy has made to the understanding of matter, and at the same time it signalled the dawn of a new age in microscopy. What we are seeing is a revolution in microscopy and a redefinition of the concept of a microscope.Several kinds of scanning probe microscopes now exist, and the number is increasing. What they share in common is a small probe that is scanned over the surface of a specimen and measures a physical property on a very small scale, at or near the surface. Scanning probes can measure temperature, magnetic fields, tunneling currents, voltage, force, and ion currents, among others.

The Electrical Characterization and Physical Failure Analysis for Transistor Gate Leakage

2006 ◽  
Author(s):  
Tsung-Te Li ◽  
Chao-Chi Wu ◽  
Jung-Hsiang Chuang ◽  
Jon C. Lee
Keyword(s):  
Failure Analysis ◽  
Electrical Characterization ◽  
Physical Analysis ◽  
Gate Leakage ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Voltage Stress ◽  
Leakage Site

Abstract This article describes the electrical and physical analysis of gate leakage in nanometer transistors using conducting atomic force microscopy (C-AFM), nano-probing, transmission electron microscopy (TEM), and chemical decoration on simulated overstressed devices. A failure analysis case study involving a soft single bit failure is detailed. Following the nano-probing analysis, TEM cross sectioning of this failing device was performed. A voltage bias was applied to exaggerate the gate leakage site. Following this deliberate voltage overstress, a solution of boiling 10%wt KOH was used to etch decorate the gate leakage site followed by SEM inspection. Different transistor leakage behaviors can be identified with nano-probing measurements and then compared with simulation data for increased confidence in the failure analysis result. Nano-probing can be used to apply voltage stress on a transistor or a leakage path to worsen the weak point and then observe the leakage site easier.

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