Epitaxy of Molybdenum on Sapphire

1973 ◽  
Vol 31 ◽  
pp. 40-41
Author(s):  
J. E. O'Neal ◽  
B. B. Rath
Keyword(s):  
Deposition Temperature ◽  
Electron Beam Evaporation ◽  
Sapphire Substrates ◽  
Thermal Etching ◽  
Substrate Surfaces ◽  
Single Crystal Sapphire ◽  
Structure Orientation ◽  
Deposited Films ◽  
Reflection Electron Diffraction

Thin films of molybdenum were deposited by the electron beam evaporation method on single crystal sapphire substrates to establish the effects of substrate orientation, deposition temperature, and evaporation rate on the structure, orientation and morphology of the deposited films. The films were characterized by replication and high resolution reflection electron diffraction methods.The epitaxy of molybdenum on sapphire substrates of orientations (0001), (1012), and (1012) were studied over a substrate temperature range of 25 through 1000°C with deposition rates of 500 and 1000 Å/min. Strain-free substrate surfaces were prepared by removing the disturbed surface layer by means of thermal etching in-situ at 1450°C for 2 hours in a pressure of 10−9 Torr.

Hetero-Epitaxy of Group Va Metals on Sapphire

1972 ◽  
Vol 30 ◽  
pp. 492-493
Author(s):  
J. E. O'Neal ◽  
J. J. Bellina ◽  
B. B. Rath
Keyword(s):  
Thermal Contact ◽  
High Vacuum ◽  
Electron Beam Evaporation ◽  
Ultra High Vacuum ◽  
Backing Plate ◽  
Sapphire Substrates ◽  
Deposition Parameters ◽  
Polishing Damage ◽  
Reflection Electron Diffraction

Thin films of the bcc metals vanadium, niobium and tantalum were epitaxially grown on (0001) and sapphire substrates. Prior to deposition, the mechanical polishing damage on the substrates was removed by an in-situ etch. The metal films were deposited by electron-beam evaporation in ultra-high vacuum. The substrates were heated by thermal contact with an electron-bombarded backing plate. The deposition parameters are summarized in Table 1.The films were replicated and examined by electron microscopy and their crystallographic orientation and texture were determined by reflection electron diffraction. Verneuil-grown and Czochralskigrown sapphire substrates of both orientations were employed for each evaporation. The orientation of the metal deposit was not affected by either increasing the density of sub-grain boundaries by about a factor of ten or decreasing the deposition rate by a factor of two. The results on growth epitaxy are summarized in Tables 2 and 3.

Thin Film Superconducting MgB2 Grown by MBE without Post-Anneal

2001 ◽  
Vol 689 ◽  
Author(s):  
William Jo ◽  
Jeong-Uk Huh ◽  
Tsuyoshi Ohnishi ◽  
Ann F. Marshall ◽  
Malcolm R. Beasley ◽  
...  
Keyword(s):  
Deposition Temperature ◽  
Molecular Beam ◽  
Electron Beam Evaporation ◽  
Superconducting Transition ◽  
Full Width ◽  
Half Maximum ◽  
Plan View ◽  
Sapphire Substrates ◽  
Transmission Electron

ABSTRACTWe report the synthesis of superconducting MgB2 thin films grown in-situ by molecular beam epitaxy (MBE). Mg-rich fluxes are deposited with B-flux by electron beam evaporation onto c- and r-plane sapphire substrates. Deposition temperature is varied between 260 ∼ 320 °C. Base pressure of the MBE chamber is at low 10-10 Torr, rising to 10-8 Torr during deposition due mostly to the presence of hydrogen and nitrogen. Asgrown MgB2 films show superconducting transition at ∼ 34 K with ΔTc < 1 K. The films on c-plane sapphire substrates exhibit c-axis oriented peaks of MgB2, and full-width at half maximum of 3 degree in their rocking curves. Azimuthal phi-scan of the MgB2(101) peak shows 12-fold symmetric peaks, which is confirmed by selected area diffraction pattern in transmission electron microscopy (TEM). Plan-view TEM shows hexagonal-shaped grain growth with grain size of about 400 Å.

In-Situ Fluorescence Strain Sensing of the Stress in Interconnects

1994 ◽  
Vol 356 ◽  
Author(s):  
Q. Wen ◽  
Q. Ma ◽  
D. R. Clarke
Keyword(s):  
Laser Beam ◽  
Frequency Shift ◽  
Sapphire Substrate ◽  
Deposition Temperature ◽  
Spectroscopic Properties ◽  
Optical Microscope ◽  
Strain Sensing ◽  
Sapphire Substrates ◽  
Optical Fluorescence

AbstractAn optical fluorescence method is introduced for determining the localized stresses in passivated aluminum lines on sapphire substrates containing a thin epitaxial ruby film at the AI/AI2O3 interface. The method is based on the piezo-spectroscopic properties of the ruby film, which acts as an in situ sensor. By focusing a laser beam through the sapphire substrate and onto the bottom of an aluminum line, the fluorescence from the ruby sensor can be excited and collected through an optical microscope. The frequency shift of the fluorescence lines is proportional to the stress in the aluminum line. To illustrate our observations two sets of measurements are presented: the spatial variation perpendicular to an interconnect line; and the temperature dependence on heating upto the deposition temperature of the SiN used to passivate the interconnects.

Ion Thinning of Electron Transparent Single Crystal Sapphire Substrates

1974 ◽  
Vol 32 ◽  
pp. 468-469
Author(s):  
J. L. Kenty ◽  
R. E. Johnson
Keyword(s):  
Thin Film ◽  
Single Crystal ◽  
Film Growth ◽  
Ion Beam ◽  
Thin Film Growth ◽  
Sapphire Substrates ◽  
Single Crystal Sapphire ◽  
Growth Experiments

Samples of single crystal sapphire (α-Al2O3) have been ion-beam thinned to yield electron transparent regions suitable for use as substrates for in situ thin film growth experiments. Routine fabrication of 1 mm dia. samples containing one or more thin (∼200Å) regions ∼10μm2 in area was possible. The samples were surprisingly robust, many surviving post-thinning subdivision, mounting into a TEM environment cell, and heating to ∼1200°C.

Controlled Planar Interface Synthesis by Ultrahigh Vacuum Diffusion Bonding/deposition

2000 ◽  
Vol 15 (4) ◽  
pp. 1008-1016 ◽  
Author(s):  
M. J. Kim ◽  
R. W. Carpenter ◽  
M. J. Cox ◽  
J. Xu
Keyword(s):  
Stainless Steel ◽  
Diffusion Bonding ◽  
Ion Beam ◽  
Ultrahigh Vacuum ◽  
Electron Beam Evaporation ◽  
Type Specimens ◽  
Interfacial Layers ◽  
Interface Synthesis ◽  
Substrate Surfaces

An ultrahigh vacuum (UHV) diffusion bonding/deposition instrument was designed and constructed, which can produce homophase and heterophase planar interfaces from a wide array of materials. The interfaces are synthesized in situ by diffusion bonding of two substrates with or without various interfacial layers, at temperatures up to about 1500 °C. Substrate surfaces can be heat treated, ion-beam sputter cleaned, and chemically characterized in situ by Auger electron spectroscopy prior to deposition and/or bonding. Bicrystals can be synthesized by bonding two single-crystal substrates at a specified orientation. Interfacial layers can be deposited by electron beam evaporation and/or sputter deposition in any layered or alloyed combination on the substrates before bonding. The instrument can accommodate cylindrical and/or wafer type specimens whose sizes are sufficient for fracture mechanical testing to measure interface bond strength. A variety of planar interfaces of metals, semiconductors, and ceramics were synthesized. Examples of bonded stainless steel/Ti/stainless steel, Si/Si, and sapphire/sapphire interfaces are presented.

Growth of Tl-2212 Films on CeO2-Buffered Sapphire Substrates

2011 ◽  
Vol 197-198 ◽  
pp. 466-470
Author(s):  
Qing Lian Xie ◽  
Hong Wei Yue ◽  
Zi Qian Huang ◽  
Guo Hua Huang ◽  
Lu Ji ◽  
...  
Keyword(s):  
Deposition Temperature ◽  
Smooth Surface ◽  
Buffer Layers ◽  
Dc Magnetron Sputtering ◽  
Axis Orientation ◽  
Sapphire Substrates ◽  
Post Annealing ◽  
Two Temperature ◽  
Annealing Method

Tl2Ba2CaCu2O8(Tl-2212) films were prepared on r-cut sapphire substrates buffered with CeO2by dc magnetron sputtering and post-annealing method. Thein situtwo-temperature process was used to grow CeO2buffer layers. XRD and AFM measurements showed that CeO2films deposited at temperature of 370-470°C were excellent c-axis orientation and had smooth surface. SEM observations demonstrated that the Tl-2212 films’ surface morphology was changed from condensing crystal structure to plate-like structure when the CeO2deposition temperature was increased. The best Tl-2212 film’s critical temperature Tccan reach to 108.3 K, and critical current density Jcobtained at 5.33 MA/cm2(77 K, 0 T).

In-situ study of the stiffness of alumina thin films during vapor deposition

2001 ◽  
Vol 672 ◽  
Author(s):  
Joris Proost ◽  
Frans Spaepen
Keyword(s):  
Thin Films ◽  
Average Rate ◽  
Electron Beam Evaporation ◽  
Refractive Indices ◽  
Final Thickness ◽  
In Situ Study ◽  
Sapphire Substrates ◽  
A Value ◽  
Amorphous Alumina

ABSTRACTThe evolution of the biaxial modulus of amorphous alumina thin films has been studied insitu during electron-beam evaporation at 400°C on Si and sapphire substrates. A constant value of 197 ± 30 GPa was measured up to a thickness of 1.17 μm when depositing at 3 Å/s. This value was identical to that of films thinner than 0.30 μm deposited at an average rate of 6 Å/s. Above 0.30 μm, the modulus in these films decreased continuously to a value of 50 ± 8 GPa at a final thickness of 2.05 μm. Based on their refractive indices, the films deposited at 6 Å/s are 30% less dense than those deposited at 3 Å/s. This density deficit is insufficient to account for the modulus decrease; the remainder is probably the result of slit-like microcracks.

Efficiency enhancement of Sb2Se3 solar cells based on electron beam evaporation CdS film with variable deposition temperature

Solar Energy ◽  
2021 ◽  
Vol 224 ◽  
pp. 875-882
Author(s):  
Huafei Guo ◽  
Xiaosong Du ◽  
Zhengdon Feng ◽  
Jiayi Zhang ◽  
Xiuqing Wang ◽  
...  
Keyword(s):  
Electron Beam ◽  
Solar Cells ◽  
Deposition Temperature ◽  
Electron Beam Evaporation ◽  
Efficiency Enhancement ◽  
Cds Film

In Situ Doping of 3C-SiC Grown on (0001) Sapphire Substrates by LPCVD

2002 ◽  
Vol 389-393 ◽  
pp. 339-342 ◽  
Author(s):  
Guo Sheng Sun ◽  
M.C. Luo ◽  
Lei Wang ◽  
S.R. Zhu ◽  
Jin Min Li ◽  
...  
Keyword(s):  
Sapphire Substrates

scholarly journals Suppressing the Initial Growth of Sidewall GaN by Modifying Micron-Sized Patterned Sapphire Substrate with H3PO4-Based Etchant

Micromachines ◽  
2018 ◽  
Vol 9 (12) ◽  
pp. 622 ◽  
Author(s):  
Wen-Yang Hsu ◽  
Yuan-Chi Lian ◽  
Pei-Yu Wu ◽  
Wei-Min Yong ◽  
Jinn-Kong Sheu ◽  
...  
Keyword(s):  
Sapphire Substrate ◽  
Light Emitting Diodes ◽  
Ex Situ ◽  
Initial Growth ◽  
Patterned Sapphire Substrate ◽  
Light Emitting ◽  
Sapphire Substrates ◽  
Patterned Sapphire Substrates

Micron-sized patterned sapphire substrates (PSS) are used to improve the performance of GaN-based light-emitting diodes (LEDs). However, the growth of GaN is initiated not only from the bottom c-plane but also from the sidewall of the micron-sized patterns. Therefore, the coalescence of these GaN crystals creates irregular voids. In this study, two kinds of nucleation layers (NL)—ex-situ AlN NL and in-situ GaN NL—were used, and the growth of sidewall GaN was successfully suppressed in both systems by modifying the micron-sized PSS surface.

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