Preparation and Characterization of Epitaxial Yttrium Silicide on (111) Silicon

1987 ◽  
Vol 91 ◽  
Author(s):  
M. Gurvitch ◽  
A. F. J. Levi ◽  
R. T. Tung ◽  
S. Nakahara
Keyword(s):  
Schottky Barrier ◽  
Mean Free Path ◽  
Surface Cleaning ◽  
Preparation Technique ◽  
Electrical Measurements ◽  
Temperature Dependent ◽  
Cleaning Procedures ◽  
The Mean ◽  
Sputter Deposited

AbstractEpitaxial YSi2-x films have been fabricated. The smooth ∼430 Å thick silicide films on Si(111) substrates were characterized by a Rutherford backscattering minimum channeling yield, Xmin = 8%. The best previously reported result, Xmin = 26%, was achieved using a relatively exotic e-beam heating method. By contrast we formed YSi2-x using a straightforward furnace annealing technique. We used improved Si surface cleaning procedures, sputter-deposited Y films, and performed two-stage anneals in a vacuum of ∼ 10−8 torr. The results of our work establish YSi2-x as one of the best epitaxial silicides. We describe our preparation technique as well as the evidence for epitaxy. Electrical measurements (Schottky barrier, temperature dependent resistivity, Hall effect) are also presented. Low temperature resistivity of YSi2-x is found to obey simple T5 Bloch's law. Based on resistivity data, YSi2-x appears to have a Debye temperature of 310 K. According to Hall measurements, it is an electronic conductor with n = 2.7 × 1022 cm−3 and the mean free path of electrons is ∼ 87 Å at 4.2 K. We measure a Schottky barrier height of 0.36 eV between YSi2-x, and n-type Si.

Planetary aerosol electrification: Lessons learned from a terrestrial analogy for Venus

2021 ◽  
Author(s):  
Amethyst Johnson ◽  
Karen Aplin
Keyword(s):  
Atmospheric Stability ◽  
Ionic Mobility ◽  
Mean Free Path ◽  
Lessons Learned ◽  
Lower Atmosphere ◽  
Aerosol Layer ◽  
Electrical Measurements ◽  
Near Surface ◽  
Charged Aerosol ◽  
The Mean

<p>Planetary atmospheric electrification has the potential to damage spacecraft, yet for planets with thick, deep atmospheres such as Venus, the level of electrification remains open to interpretation. Partly due to the difficulty of access and potential hostility to spacecraft, there are limited in-situ observations of deep atmospheres, making terrestrial analogies attractive. One proposed explanation of the observations of near-surface electrification on Venus from sensors on Venera 13 & 14 is a haze of charged aerosol. As the Sahara is an environment with lofted dust that is potentially similar to Venus in terms of atmospheric stability, a simple model was developed estimating a mean aerosol charge based on typical Saharan haze aerosol distributions. Spacecraft surface area and descent speeds were used to estimate the accumulated charge and discharge current measured by the Venera missions, but this model underestimated Venera's electrical measurements by three orders of magnitude. This suggests that an aerosol layer alone cannot explain the charge apparently present in the lower atmosphere of Venus. The simple terrestrial analogy employed may not have been suitable due to the modified pressure and temperature profile affecting the mean free path, ionic mobility and consequently the mean charge. Discrepancies in atmospheric stability and wind patterns must also be evaluated, as the effect of terrestrial wind on aerosol distributions may not be directly applicable to other planets. More detailed calculations of ion-aerosol attachment and re-evaluation of the terrestrial analogy may be able to resolve some these issues, but it looks likely that additional significant sources of charge are required to explain the Venera observations. Triboelectric charging of lofted surface material could exceed charging observed in terrestrial situations, or some unknown atmospheric or non-atmospheric source of charge could have contributed to the Venera electrical measurements. </p>

Performance of Pt-based Low Schottky Barrier Silicide Contacts on Weakly Doped Silicon

2003 ◽  
Vol 765 ◽  
Author(s):  
Guilhem Larrieu ◽  
Emmanuel Dubois ◽  
Xavier Wallart
Keyword(s):  
Schottky Barrier ◽  
Cross Sections ◽  
Ohmic Contacts ◽  
Thermionic Emission ◽  
Current Drive ◽  
Silicon On Insulator ◽  
Grand Challenge ◽  
Electrical Measurements ◽  
Temperature Dependent ◽  
Current Voltage

AbstractOne of the grand challenge imposed by CMOS down-scaling is the optimisation of the source/drain (S/D) architecture, e.g., dopant activation above solid solubility, steep dopant profiling, low silicide specific contact resistivity. Recently, the concept of very low Schottky barrier S/D MOSFET has emerged as a possible alternative to conventional architecture using highly doped S/D and midgap silicide ohmic contacts. For p-MOSFETs integration, platinum silicide is an excellent candidate because of its very low barrier to holes. This enables the use of a weakly doped substrate that inherently solves the aforementioned challenges due to highly doped S/D. This paper proposes a detailed study of the platinum silicidation reaction obtained by rapid thermal annealing. The analysis is based on X-ray photoemission spectroscopy (XPS), transmission electron miscrocopy (TEM) and low temperature-dependent current-voltage measurements. Using XPS analysis, it is shown that: i) an initial silicide layer is formed at room temperature, ii) three stable phases Pt, Pt2Si, PtSi can not coexist providing that iii) the annealing ambience is strictly controlled to avoid the formation of a SiO2 barrier due to oxygen penetration into the platinum overlayer. Starting from an initial 15 nm thick Pt layer subsequently annealing at 300°C, TEM cross-sections reveal that homogeneous 32 nm PtSi layers with a uniform grain size distribution are formed. Finally, current-voltage characteristics have been measured on a special test structure that accounts for the lateral disposition of S/D regions in a typical MOSFET architecture. It consists in two back-to-back Schottky contacts separated by a narrow silicon gap both on bulk silicon and Silicon-On-Insulator (SOI) substrates. Based on temperature-dependent electrical measurements (Arrhenius plot), it is shown that field emission is involved in the current transport mechanism, in addition to thermionic emission. An excellent current drive performance of 220 μA per micron width has been obtained for a 45 nm silicon gap on a 10 nm thick SOI substrate.

Design, Fabrication and Characterization of 1.5 mΩcm2, 800 V 4H-SiC n-Type Schottky Barrier Diodes

2005 ◽  
Vol 483-485 ◽  
pp. 941-944 ◽  
Author(s):  
M. Furno ◽  
F. Bonani ◽  
G. Ghione ◽  
Sergio Ferrero ◽  
Samuele Porro ◽  
...  
Keyword(s):  
Experimental Study ◽  
Numerical Simulations ◽  
Schottky Barrier ◽  
Epitaxial Layers ◽  
Schottky Barrier Diodes ◽  
Electrical Measurements ◽  
Process Technology ◽  
Edge Termination ◽  
Fabrication And Characterization

We present a theoretical and experimental study on the design, fabrication and characterization of Schottky Barrier Diodes (SBD) on commercial 4H-SiC epitaxial layers. Numerical simulations were performed with a commercial tool on different edge termination structures, with the aim of optimizing the device behavior. For each termination design, SBD were fabricated and characterized by means of electrical measurements vs. temperature. Simulations provided also useful data for the assessment of the device process technology.

TEM characterization of silicon epitaxial layer grown on Si-TaS2, eutectic composites

1991 ◽  
Vol 49 ◽  
pp. 802-803
Author(s):  
C.M. Sung ◽  
M. Levinson ◽  
M. Tabasky ◽  
K. Ostreicher ◽  
B.M. Ditchek
Keyword(s):  
Substrate Surface ◽  
Bulk Sample ◽  
Surface Cleaning ◽  
Native Oxide ◽  
Czochralski Growth ◽  
Ion Milling ◽  
Cross Sectional ◽  
Cleaning Methods ◽  
Field Emission Cathodes

Directionally solidified Si/TaSi2 eutectic composites for the development of electronic devices (e.g. photodiodes and field-emission cathodes) were made using a Czochralski growth technique. High quality epitaxial growth of silicon on the eutectic composite substrates requires a clean silicon substrate surface prior to the growth process. Hence a preepitaxial surface cleaning step is highly desirable. The purpose of this paper is to investigate the effect of surface cleaning methods on the epilayer/substrate interface and the characterization of silicon epilayers grown on Si/TaSi2 substrates by TEM.Wafers were cut normal to the <111> growth axis of the silicon matrix from an approximately 1 cm diameter Si/TaSi2 composite boule. Four pre-treatments were employed to remove native oxide and other contaminants: 1) No treatment, 2) HF only; 3) HC1 only; and 4) both HF and HCl. The cross-sectional specimens for TEM study were prepared by cutting the bulk sample into sheets perpendicular to the TaSi2 fiber axes. The material was then prepared in the usual manner to produce samples having a thickness of 10μm. The final step was ion milling in Ar+ until breakthrough occurred. The TEM samples were then analyzed at 120 keV using the Philips EM400T.

Applications of ultramicrotomy for materials characterization

1993 ◽  
Vol 51 ◽  
pp. 232-233
Author(s):  
R.T. Blackham ◽  
J.J. Haugh ◽  
C.W. Hughes ◽  
M.G. Burke
Keyword(s):  
Materials Science ◽  
Microstructural Analysis ◽  
Analytical Electron Microscopy ◽  
Austenitic Stainless Steels ◽  
Specimen Preparation ◽  
Preparation Technique ◽  
Thermally Induced ◽  
Radiation Induced ◽  
Characterization Of Materials

Essential to the characterization of materials using analytical electron microscopy (AEM) techniques is the specimen itself. Without suitable samples, detailed microstructural analysis is not possible. Ultramicrotomy, or diamond knife sectioning, is a well-known mechanical specimen preparation technique which has been gaining attention in the materials science area. Malis and co-workers and Glanvill have demonstrated the usefulness and applicability of this technique to the study of a wide variety of materials including Al alloys, composites, and semiconductors. Ultramicrotomed specimens have uniform thickness with relatively large electron-transparent areas which are suitable for AEM anaysis.Interface Analysis in Type 316 Austenitic Stainless Steel: STEM-EDS microanalysis of grain boundaries in austenitic stainless steels provides important information concerning the development of Cr-depleted zones which accompany M23C6 precipitation, and documentation of radiation induced segregation (RIS). Conventional methods of TEM sample preparation are suitable for the evaluation of thermally induced segregation, but neutron irradiated samples present a variety of problems in both the preparation and in the AEM analysis, in addition to the handling hazard.

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