The Use of Leed for the Characterization of Surface Damage from Pulsed Laser Irradiation

1985 ◽  
Vol 48 ◽  
Author(s):  
Aubrey L. Helms ◽  
Chin-Chen Cho ◽  
Steven L. Bernasek ◽  
Clifton W. Draper
Keyword(s):  
Thermal Stresses ◽  
Profile Analysis ◽  
High Vacuum ◽  
Surface Damage ◽  
Laser Pulses ◽  
Ultra High Vacuum ◽  
Crystal Surfaces ◽  
Single Crystal Surfaces ◽  
Laser Fluences ◽  
Dislocation Sources

ABSTRACTLow Energy Electron Diffraction (LEED)-Spot Profile Analysis and Auger Electron Spectroscopy (AES) have been used to study the response of Mo(100) single crystal surfaces to Q-switched, frequency doubled Nd:YAG laser pulses. The experiments were conducted in a special ultra-high vacuum (UHV) system which allowed the surfaces to be irradiated under controlled conditions. Laser fluences both above and below the melt threshold were employed. For the melted surfaces, good epitaxial regrowth was observed. The spot profile analysis indicates the formation of random islands on the surfaces. Surfaces which had been previously disordered by 3 KeV Ar+ implantation were laser surface melted and observed to regrow epitaxially as has been observed in the case of ion implanted silicon. The formation of the islands and stepped structures is explained by considering the activation of dislocation sources by the induced thermal stresses resulting in slip.

Tuning the surface structure and conductivity of niobium-doped rutile TiO2 single crystals via thermal reduction

2017 ◽  
Vol 19 (45) ◽  
pp. 30339-30350 ◽  
Author(s):  
D. Wrana ◽  
C. Rodenbücher ◽  
M. Krawiec ◽  
B. R. Jany ◽  
J. Rysz ◽  
...  
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
Structural Changes ◽  
High Vacuum ◽  
Thermal Reduction ◽  
Ultra High Vacuum ◽  
Crystal Surfaces ◽  
Single Crystal Surfaces ◽  
Systematic Exploration ◽  
Niobium Doped

We report on the systematic exploration of electronic and structural changes of Nb-doped rutile TiO2(110) single crystal surfaces due to the thermoreduction under ultra-high vacuum conditions (without sputtering), with comparison to undoped TiO2(110) crystals.

Heteroepitaxial Growth of MgO Films on NiO(100) Single Crystal Surfaces

1994 ◽  
Vol 357 ◽  
Author(s):  
S. Imaduddin ◽  
A.M. Davidson ◽  
R.J. Lad
Keyword(s):  
Single Crystal ◽  
Lattice Mismatch ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Heteroepitaxial Growth ◽  
Crystal Surfaces ◽  
Single Crystal Surfaces ◽  
Oxygen Anions ◽  
Mgo Layers

AbstractEpitaxial MgO layers were grown on cleaved NiO(100) single crystal surfaces. The less than 1% lattice mismatch between MgO and NiO allows almost ideal epitaxy of MgO at 100°C. The epitaxial films were created by dosing Mg onto stoichiometric NiO(100) both in ultra-high vacuum (UHV) and in an O2 atmosphere (5×10−7 Torr). Chemical interactions at the resulting interfaces were studied using XPS. When Mg is dosed onto NiO(100) in UHV, MgO forms by interacting with oxygen anions in the NiO substrate thereby reducing the nickel cations. Metallic Mg layers begin to form upon subsequent dosing. When Mg is deposited in O2, epitaxial MgO(100) layers grow to a thickness of at least 50Å as confirmed by in situ RHEED and LEED observations. Negligible intermixing between the MgO and NiO is observed during growth at 100°C and on subsequent annealing in UHV up to 600°C.

Laser-Induced Desorption of in and Ga from Si(100) and Adsorbate Enhanced Surface Damage

1991 ◽  
Vol 236 ◽  
Author(s):  
Paul G. Strupp ◽  
April L. Alstrin ◽  
Brenda J. Korte ◽  
Stephen R. Leone
Keyword(s):  
High Vacuum ◽  
Surface Damage ◽  
Laser Pulses ◽  
Laser Induced Fluorescence ◽  
Ultra High Vacuum ◽  
Two Dimensional ◽  
Adsorbate Layer ◽  
Exponential Factors ◽  
Enhanced Surface ◽  
532 Nm

AbstractLaser-induced desorption (LID) of In and Ga from Si(100) under ultra-high vacuum conditions is investigated. The frequency doubled 532 nm, 2-6 ns output of a Nd:YAG laser is focussed to 0. 14±0.03 J/cm2 on the Si surface to induce desorption. Desorbed In or Ga atoms are detected by laser-induced fluorescence initiated by a pulsed dye laser propagating in front of the surface. LID occurs by thermal desorption with approximate desorption energies and pre-exponential factors in agreement with literature values from previous isothermal desorption measurements. Experiments at higher coverages suggest that desorption occurs predominantly from the two-dimensional (2D) adsorbate layer with little desorption occurring directly from adsorbate islands. The 2D layer is resupplied by either diffusion out of adsorbate islands or by diffusion of incorporated adsorbate out of the bulk. Adsorbate-enhanced laser-induced surface damage is also observed; only 0.2 monolayer of In reduces the number of laser pulses required to observe damage by greater than a factor of 30.

An ultra high vacuum system for thin dielectric film deposition at low temperatures

1988 ◽  
Vol 3 (5) ◽  
pp. 951-957
Author(s):  
R. P. H. Chang ◽  
G. Griffiths
Keyword(s):  
Low Temperatures ◽  
High Vacuum ◽  
Oxide Films ◽  
Film Deposition ◽  
Ultra High Vacuum ◽  
Oxide Semiconductor ◽  
Vacuum System ◽  
Phosphorus Oxide ◽  
Electrical Measurements ◽  
Crystal Surfaces

An ultra high vacuum system has been designed and constructed for the purpose of depositing high-quality oxide films on well-characterized crystal surfaces at low temperatures. In particular, aluminum phosphorus oxide films have been deposited on both In P and Ge surfaces for the purpose of device application. Electrical measurements of metal-oxide-semiconductor structures show much improved interfacial properties with little or no hysteresis.

Modification of a TEM for ultra-high-vacuum reflection-EM (UHV-REM) applications

1995 ◽  
Vol 53 ◽  
pp. 582-583
Author(s):  
Tung Hsu ◽  
Min-Yi Shih ◽  
A. V. Latyshev
Keyword(s):  
Electron Microscope ◽  
High Vacuum ◽  
High Energy ◽  
Ultra High Vacuum ◽  
Objective Lens ◽  
Pole Piece ◽  
High Energy Electron ◽  
Normal Position ◽  
Crystal Surfaces ◽  
Specimen Holder

A JEOL JEM-100C electron microscope was modified by adding a cryogenic UHV specimen holder for studying clean crystal surfaces with the reflection high energy electron diffraction (RHEED) and REM techniques. The Si(111) (l×l) and (7×7) phase transitions have been successfully observed (Fig. 1). Further modification is in progress for better resolution and other functions. Fig. 2.a shows the unmodified specimen holder and the objective lens of the microscope. The cryogenic holder based on the Novosibirsk design is shown in Fig. 2.b. Liquid nitrogen is continuously pumped through the shell of the holder for achieving UHV inside. The tilt/rotation controls and the current for heating of the specimen are fed through the holder. In this modification, the specimen was not placed at the normal position of the lens and therefore is not at the best position for imaging and diffraction.A new holder is shown in Fig. 2.c. This holder is inserted into the pole piece to place the specimen at the normal position.

A compact UHV X-ray diffractometer for studying surfaces and interfaces

1998 ◽  
Vol 5 (3) ◽  
pp. 887-889
Author(s):  
Yoshikazu Fujii ◽  
Takeshi Nakamura ◽  
Mutsumi Kai ◽  
Kentaroh Yoshida
Keyword(s):  
High Vacuum ◽  
Layer Growth ◽  
Ultra High Vacuum ◽  
Layer By Layer ◽  
Crystal Surfaces ◽  
X Ray ◽  
Surfaces And Interfaces ◽  
Optical Table ◽  
Specimen Orientation

A compact ultra-high-vacuum (UHV) X-ray diffractometer for surface glancing X-ray scattering has been constructed. All the equipment, including a rotating-anode source of 18 kW and a UHV specimen chamber, is arranged on one optical table of dimensions 70 × 90 cm. The specimen chamber is 14 cm in diameter and 20 cm high and can be evacuated up to 3 × 10−8 Pa. It is equipped with two Be windows of thicknesses 0.2 and 0.4 mm. Specimen orientation in the vacuum is controlled from the outside. The specimen can be heated up to 773 K. The chamber has two evaporation cells and can be used for in situ observations of growing crystal surfaces. Using this instrument, we observed a mechanically polished Ag surface and successfully made an in situ observation of the layer-by-layer growth of a PbSe(111) surface. The instrument will be useful for preliminary experiments using laboratory sources, prior to final measurements at synchrotron radiation facilities.

Magnetic Anisotropy of Co Films Annealed by Laser Pulses

2008 ◽  
Vol 140 ◽  
pp. 69-74 ◽  
Author(s):  
J. Kisielewski ◽  
Kamil Postava ◽  
I. Sveklo ◽  
A. Nedzved ◽  
P. Trzciński ◽  
...  
Keyword(s):  
Magnetic Anisotropy ◽  
High Vacuum ◽  
Pulsed Laser ◽  
Perpendicular Magnetic Anisotropy ◽  
Laser Pulses ◽  
Ultra High Vacuum ◽  
Mica Substrate ◽  
Induced Magnetic Anisotropy ◽  
Coercivity Field ◽  
Pulsed Laser Beam

The magnetic properties of an ultrathin cobalt film were modified by a focused femtosecond pulsed laser beam. The Co wedge, with a thickness ranging from 0 to 2 nm, sandwiched by Au films was prepared using ultra-high vacuum magnetron sputtering on a mica substrate. The modifications of the laser induced magnetic anisotropy were investigated using magneto-optic Kerr microscopy and MFM/AFM techniques. The laser induces: (i) local reorientation of magnetization from an in-plane to a perpendicular state and (ii) an increase of the coercivity field. A corresponding increase of the perpendicular magnetic anisotropy is discussed considering an improvement of the Co/Au interfaces.

STM Study of Self-assembly of Quantum Dot Formed by Selective Laser Heating

2013 ◽  
Vol 1527 ◽  
Author(s):  
Haeyeon Yang ◽  
Casey M. Clegg
Keyword(s):  
Self Assembly ◽  
High Vacuum ◽  
Laser Pulses ◽  
Ultra High Vacuum ◽  
Scanning Tunneling ◽  
Mbe Growth ◽  
Optical Wavelength ◽  
Growth Method ◽  
Dot Density ◽  
Average Size

ABSTRACTScanning Tunneling Microscope (STM) was used to examine the morphologies of selfassembled InGaAs quantum dots (QDs). In order to induce the self-assembly, unlike the conventional Stranski-Krastanov (S-K) growth method, spatial thermal modulations in nanoscale were created in-situ on strained-but-flat InGaAs surfaces in a Molecular Beam Epitaxy (MBE) growth reactor by applying interferential irradiations of laser pulses (IILP). As-irradiated surfaces were examined using an attached ultra-high vacuum (UHV) STM. STM images indicate that the irradiation of 7 nano second laser pulse induces self-assembly of QDs. The average size of laser-induced QDs is smaller while their density is larger than that of QDs formed by annealing strained but flat epilayers conventionally. Furthermore, the dot density is modulated sinusoidally with a periodicity commensurate with that of the interference, which suggests that the placement of QDs can be controlled on the scale of the optical wavelength used. QD volume analysis suggests that dots grow faster laterally than vertically so that dots become flattened as they get larger.

scholarly journals Femtosecond-Laser Nanostructuring of Black Diamond Films under Different Gas Environments

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5761
Author(s):  
Marco Girolami ◽  
Alessandro Bellucci ◽  
Matteo Mastellone ◽  
Stefano Orlando ◽  
Valerio Serpente ◽  
...  
Keyword(s):  
Optical Properties ◽  
High Vacuum ◽  
Diamond Films ◽  
Cost Effective ◽  
Laser Pulses ◽  
Ultra High Vacuum ◽  
Infrared Light ◽  
Ambient Conditions ◽  
Combined Use ◽  
Fs Laser

Irradiation of diamond with femtosecond (fs) laser pulses in ultra-high vacuum (UHV) conditions results in the formation of surface periodic nanostructures able to strongly interact with visible and infrared light. As a result, native transparent diamond turns into a completely different material, namely “black” diamond, with outstanding absorptance properties in the solar radiation wavelength range, which can be efficiently exploited in innovative solar energy converters. Of course, even if extremely effective, the use of UHV strongly complicates the fabrication process. In this work, in order to pave the way to an easier and more cost-effective manufacturing workflow of black diamond, we demonstrate that it is possible to ensure the same optical properties as those of UHV-fabricated films by performing an fs-laser nanostructuring at ambient conditions (i.e., room temperature and atmospheric pressure) under a constant He flow, as inferred from the combined use of scanning electron microscopy, Raman spectroscopy, and spectrophotometry analysis. Conversely, if the laser treatment is performed under a compressed air flow, or a N2 flow, the optical properties of black diamond films are not comparable to those of their UHV-fabricated counterparts.

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