scholarly journals High-Selectivity Growth of GaN Nanorod Arrays by Liquid-Target Magnetron Sputter Epitaxy

Coatings ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 719
Author(s):  
Elena Alexandra Serban ◽  
Aditya Prabaswara ◽  
Justinas Palisaitis ◽  
Per Ola Åke Persson ◽  
Lars Hultman ◽  
...  
Keyword(s):  
Growth Rate ◽  
Focused Ion Beam ◽  
High Selectivity ◽  
Ion Beam ◽  
Substrate Surface ◽  
Growth Control ◽  
High Growth ◽  
Si Substrates ◽  
Surface Diffusivity ◽  
Magnetron Sputter

Selective-area grown, catalyst-free GaN nanorod (NR) arrays grown on Si substrates have been realized using liquid-target reactive magnetron sputter epitaxy (MSE). Focused ion beam lithography (FIBL) was applied to pattern Si substrates with TiNx masks. A liquid Ga target was sputtered in a mixture gas of Ar and N2, ranging the N2 partial pressure (PN₂) ratio from 100% to 50%. The growth of NRs shows a strong correlation with PN₂ on the selectivity, coalescence, and growth rate of NRs in both radial and axial directions. The growth rate of NRs formed inside the nanoholes increases monotonically with PN₂. The PN₂ ratio between 80% and 90% was found to render both a high growth rate and high selectivity. When the PN₂ ratio was below 80%, multiple NRs were formed in the nanoholes. For a PN₂ ratio higher than 90%, parasitic NRs were grown on the mask. An observed dependence of growth behavior upon the PN₂ ratio is attributed to a change in the effective Ga/N ratio on the substrate surface, as an effect of impinging reactive species, surface diffusivity, and residence time of adatoms. The mechanism of NR growth control was further investigated by studying the effect of nanoholes array pitch and growth temperature. The surface diffusion and the direct impingement of adatoms were found to be the dominant factors affecting the lateral and axial growth rates of NR, respectively, which were well elucidated by the collection area model.

Electronic Properties of Bismuth Nanowires

2001 ◽  
Vol 679 ◽  
Author(s):  
Stephen B. Cronin ◽  
Yu-Ming Lin ◽  
Oded Rabin ◽  
Marcie R. Black ◽  
Gene Dresselhaus ◽  
...  
Keyword(s):  
Theoretical Model ◽  
Band Structure ◽  
Temperature Dependence ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Temperature Dependent ◽  
Si Substrates ◽  
Bismuth Nanowires ◽  
Bi Nanowire ◽  
Anodic Alumina Templates

ABSTRACTThe pressure filling of anodic alumina templates with molten bismuth has been used to synthesize single crystalline bismuth nanowires with diameters ranging from 7 to 200nm and lengths of 50μm. The nanowires are separated by dissolving the template, and electrodes are affixed to single Bi nanowires on Si substrates. A focused ion beam (FIB) technique is used first to sputter off the oxide from the nanowires with a Ga ion beam and then to deposit Pt without breaking vacuum. The resistivity of a 200nm diameter Bi nanowire is found to be only slightly greater than the bulk value, while preliminary measurements indicate that the resistivity of a 100nm diameter nanowire is significantly larger than bulk. The temperature dependence of the resistivity of a 100nm nanowire is modeled by considering the temperature dependent band parameters and the quantized band structure of the nanowires. This theoretical model is consistent with the experimental results.

Formation of Sub-100 NM GE Wires on Si by E-Beam Evaporation/Lithography

1995 ◽  
Vol 380 ◽  
Author(s):  
C. Deng ◽  
J. C. Wu ◽  
C. J. Barbero ◽  
T. W. Sigmon ◽  
M. N. Wybourne
Keyword(s):  
Cross Section ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Si Substrates ◽  
Novel Technique ◽  
Atomic Force ◽  
Transmission Electron ◽  
First Time ◽  
Scanning Electron

ABSTRACTA fabrication process for sub-100 nm Ge wires on Si substrates is reported for the first time. Wires with a cross section of 6 × 57 nm2 are demonstrated. The wire structures are analyzed by atomic force (AFM), scanning electron (SEM), and transmission electron microscopy (TEM). Sample preparation for TEM is performed using a novel technique using both pre and in situ deposition of multiple protection layers using a Focused Ion Beam (FIB) micromachining system.

Ge dot organization on Si substrates patterned by focused ion beam

2004 ◽  
Vol 85 (26) ◽  
pp. 6401-6403 ◽  
Author(s):  
A. Karmous ◽  
A. Cuenat ◽  
A. Ronda ◽  
I. Berbezier ◽  
S. Atha ◽  
...  
Keyword(s):  
Focused Ion Beam ◽  
Ion Beam ◽  
Si Substrates

scholarly journals Optimization of Pt-C Deposits by Cryo-FIBID: Substantial Growth Rate Increase and Quasi-Metallic Behaviour

Nanomaterials ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1906 ◽  
Author(s):  
Alba Salvador-Porroche ◽  
Soraya Sangiao ◽  
Patrick Philipp ◽  
Pilar Cea ◽  
José María De Teresa
Keyword(s):  
Growth Rate ◽  
Electrical Resistivity ◽  
Room Temperature ◽  
Focused Ion Beam ◽  
Ion Irradiation ◽  
Ion Beam ◽  
Electrical Contacts ◽  
Condensation Temperature ◽  
Monte Carlo Code ◽  
Condensed Layer

The Focused Ion Beam Induced Deposition (FIBID) under cryogenic conditions (Cryo-FIBID) technique is based on obtaining a condensed layer of precursor molecules by cooling the substrate below the condensation temperature of the gaseous precursor material. This condensed layer is irradiated with ions according to a desired pattern and, subsequently, the substrate is heated above the precursor condensation temperature, revealing the deposits with the shape of the exposed pattern. In this contribution, the fast growth of Pt-C deposits by Cryo-FIBID is demonstrated. Here, we optimize various parameters of the process in order to obtain deposits with the lowest-possible electrical resistivity. Optimized ~30 nm-thick Pt-C deposits are obtained using ion irradiation area dose of 120 μC/cm2 at 30 kV. This finding represents a substantial increment in the growth rate when it is compared with deposits of the same thickness fabricated by standard FIBID at room temperature (40 times enhancement). The value of the electrical resistivity in optimized deposits (~4 × 104 µΩ cm) is suitable to perform electrical contacts to certain materials. As a proof of concept of the potential applications of this technology, a 100 µm × 100 µm pattern is carried out in only 43 s of ion exposure (area dose of 23 μC/cm2), to be compared with 2.5 h if grown by standard FIBID at room temperature. The ion trajectories and the deposit composition have been simulated using a binary-collision-approximation Monte Carlo code, providing a solid basis for the understanding of the experimental results.

scholarly journals Corrosion pitting and environmentally assisted small crack growth

2014 ◽  
Vol 470 (2169) ◽  
pp. 20140254 ◽  
Author(s):  
Alan Turnbull
Keyword(s):  
Growth Rate ◽  
Stress Corrosion ◽  
Focused Ion Beam ◽  
Imaging Techniques ◽  
Ion Beam ◽  
Critical Factor ◽  
Potential Drop ◽  
Quantitative Prediction ◽  
Local Dynamic ◽  
Element Analysis

In many applications, corrosion pits act as precursors to cracking, but qualitative and quantitative prediction of damage evolution has been hampered by lack of insights into the process by which a crack develops from a pit. An overview is given of recent breakthroughs in characterization and understanding of the pit-to-crack transition using advanced three-dimensional imaging techniques such as X-ray computed tomography and focused ion beam machining with scanning electron microscopy. These techniques provided novel insights with respect to the location of crack development from a pit, supported by finite-element analysis. This inspired a new concept for the role of pitting in stress corrosion cracking based on the growing pit inducing local dynamic plastic strain, a critical factor in the development of stress corrosion cracks. Challenges in quantifying the subsequent growth rate of the emerging small cracks are then outlined with the potential drop technique being the most viable. A comparison is made with the growth rate for short cracks (through-thickness crack in fracture mechanics specimen) and long cracks and an electrochemical crack size effect invoked to rationalize the data.

Fabricating Two-Dimensional Metal Nanocrystal Arrays Using Pulsed-Laser Deposition and Focused Ion-Beam Technologies

2000 ◽  
Vol 636 ◽  
Author(s):  
Richard F. Haglund ◽  
Robert A. Weller ◽  
Cynthia E. Heiner ◽  
Matthew D. McMahon ◽  
Robert H. Magruder ◽  
...  
Keyword(s):  
Pulsed Laser Deposition ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
High Vacuum ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
Silicon Surfaces ◽  
Silver Nanoclusters ◽  
Laser Evaporation ◽  
Si Substrates

AbstractWe describe recent experiments in which we attempted the initial steps for fabricating twodimensional arrays of metal nanocrystals. We use a commercial pulsed-laser deposition system in concert with a focused ion beam to attempt control over both lateral and vertical dimensions at the nanometer length scale. In our experiments, regular arrays of holes typically 80 nm in diameter were drilled in Si substrates using the focused ion beam. Silver atoms were then deposited onto these substrates by pulsed laser evaporation from a metallic target in high vacuum. Under certain conditions of substrate temperature, laser pulse repetition rate, and fluence, small silver nanoclusters form preferentially around the structures previously etched in the silicon surfaces by the focused ion beam.

Chemically-Enhanced GaAs Maskless Etching Using a Novel Focused Ion Beam Etching System with a Chlorine Molecular and Radical Beam

1986 ◽  
Vol 75 ◽  
Author(s):  
N. Takado ◽  
K. Asakawa ◽  
H. Arimoto ◽  
T. Morita ◽  
S. Sugata ◽  
...  
Keyword(s):  
Focused Ion Beam ◽  
Ion Beam ◽  
Substrate Surface ◽  
Maximum Yield ◽  
Laser Cavity ◽  
High Rate ◽  
Enhancement Effect ◽  
Scanning Time ◽  
Chemical Enhancement ◽  
Deep Groove

AbstractChlorine-enhanced GaAs maskless etching using a novel focused-ion-beametching (FIBE) system has been examined for establishing high-rate and smooth FIBE. The system is composed of an air-locked ultrahigh-vacuum chamber, a 30 KeV Ga+ FIB column and two kinds of chlorine-irradiation nozzles. A fine nozzle enabled us to irradiate a high-density Cl2 flux on a desired, small area of the sample while retaining a sufficiently low surrounding-gas pressure for stable Ga+ FIB emission. Highly chemically-enhanced sputtering yields (up to 50 GaAs molecules per incident ion) were obtained. At the maximum yield, line-scanned deep-groove (6.5 um) etching with a smooth surface, capable of fabricating a laser-cavity optical mirror, was demonstrated. The chemical-enhancement effect showed high FIB-scanning-time dependence. This effect was also observed by irradiating with a plasma-dissociated Cl radicals using a novel radical beam gun. An analytical model, based on the Ga+-ion bombardment on the chlorine-adsorbed substrate surface, suggested that the maximum chemical enhancement is obtained when the Ga+-FIB scanning time is adjusted to the chlorine-coverage time, given by the Cl2-molecule or Cl-radical flux density.

Sub-Micron Selective Photoluminescence in Porous Si by Focused Ion Beam Implantation

1992 ◽  
Vol 281 ◽  
Author(s):  
A. J. Steckl ◽  
J. Xu ◽  
H. C. Mogul ◽  
S. Mogren
Keyword(s):  
Incubation Time ◽  
Focused Ion Beam ◽  
Hole Concentration ◽  
Ion Beam ◽  
Porous Si ◽  
Strong Function ◽  
Si Substrates ◽  
Si Doping ◽  
Broad Beam ◽  
First Time

ABSTRACTThe effect of Si doping on the formation of stain-etched porous Si and its photoluminescent properties was studied. Porous Si is obtained by purely chemical etching of crystalline Si in a solution of HF:HNO3:H2O in the ratio of 1:3:5. We have observed that an incubation time (ti) exists between the insertion of Si into the solution and the onset of porous Si production. This incubation time was found to be a strong function of hole concentration in both n- and p-Si. In p-Si, the ti decreased rapidly with increasing conductivity, whereas for n-Si the opposite (but not as pronounced) trend was found to be the case. For example in (B-doped) p-Si, ti, is only ∼0.5 min for 250 (Ω-cm)−1 but increases to ∼ 5 min for 0.2 (Ω-cm)−1. In (P-doped) n-Si substrates ti was ∼ 8 min for 0.2 (Ω-cm)−1 increasing to ∼ 10 min for 7 (Ω-cm)−1. Photoluminescence (PL) measurements of the porous Si obtained on substrates of various conductivity (p and n) show similar spectra, namely a peak at around 1.94 eV with a full width at half-maximum (FWHM) of about 0.5 eV. Based on the ti difference, we have fabricated localized photoemitting porous Si patterns by Ga+ focused ion beam (FIB) implantation doping and B+ broad beam (BB) implantation doping of n-type Si. Using 30 kV FIB Ga+ implantation, sub-micron photoemitting patterns have been obtained for the first time.

Development of a Refractory Hexagonal Closed Packed High Entropy Alloy Based on Thin Film Screening

MRS Advances ◽  
2019 ◽  
Vol 4 (25-26) ◽  
pp. 1435-1440
Author(s):  
Azin Akbari ◽  
T. John Balk
Keyword(s):  
Thin Film ◽  
Single Phase ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
High Entropy Alloy ◽  
Electron Backscattered Diffraction ◽  
X Ray ◽  
High Entropy ◽  
Si Substrates ◽  
Hexagonal Closed Packed

In order to identify candidate high entropy alloys (HEAs) that have the hexagonal closed packed crystal structure, gradient thin films in the OsRuWMoRe system were deposited by sputtering from multiple elemental targets onto Si substrates. In addition to having compositional gradients, the films exhibited regions with different phases, some of which were single-phase and non-equiatomic. Such alloys have the potential to exhibit properties superior to the primarily equiatomic HEAs that have been the focus of most work in this area. To screen the phases that exist across the thin film gradient samples, a range of characterization techniques were employed, including focused ion beam and scanning electron microscopy, X-ray energy dispersive spectroscopy, X-ray diffraction and electron backscattered diffraction analysis. The combinatorial method described in this study enabled the identification of a candidate single-phase HEA that was subsequently fabricated as a bulk alloy.

Heteroepitaxial Self-Assembly of Higher-Complexity Structures By Combining Growth Control with Nanopatterning

2004 ◽  
Vol 849 ◽  
Author(s):  
Jerrold A. Floro ◽  
Jennifer L. Gray ◽  
Surajit Atha ◽  
Nitin Singh ◽  
Dana Elzey ◽  
...  
Keyword(s):  
Quantum Dot ◽  
Self Assembly ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Three Dimensional ◽  
Growth Control ◽  
Additional Degree ◽  
Quantum Dot Molecules ◽  
Symmetric Quantum ◽  
Dimensional Growth

ABSTRACTWe provide an overview of a novel self-assembly process that occurrs during GeSi/Si(001) strain-layer heteroepitaxy under conditions of limited adatom mobility. Suppression of copious surface diffusion leads to limited three-dimensional roughening in the form of pits that partially consume a thick, metastable wetting layer. The material ejected from the pits accumulates alongside, eventually forming a symmetric quantum dot molecule consisting of four islands bound to a {105}-faceted pit. These structures, which are of interest in nanologic applications, appear to arise from an intrinsic strain-relief mechanism in a relatively narrow regime of deposition conditions. An additional degree of morphological control is obtained by annealing films containing pits, before they evolve to full quantum dot molecules. Annealing promotes a one-dimensional growth instability leading to the formation of highly anisotropic grooves, bounded by long, wire-like islands. Finally, we show that patterns created in the Si substrate using a focused ion beam can control the location of quantum dot molecules, which is an additional critical step towards being able to use these structures for computing.

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