Characterization of the Interface Between Metal Contacts and Epilayers of Doped Silicon Carbide

1995 ◽  
Vol 405 ◽  
Author(s):  
M. A. George ◽  
D. J. Larkin ◽  
J. Petit ◽  
A. Burger ◽  
S. H. Morgan ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Ohmic Contacts ◽  
Chemical Vapor ◽  
Metal Contacts ◽  
Aluminum Films ◽  
Force Microscopy ◽  
Atomic Force ◽  
Chemical Vapor Deposited ◽  
Before And After ◽  
P Type

AbstractAluminum contacts on chemical vapor deposited (CVD) SiC films were studied to examine variations in the chemical, morphological and electrical properties of the samples. Nitrogen and aluminum doped substrates were prepared to give n-type and p-type SiC epilayers respectively. These preparations were examined by surface sensitive spectroscopies and by atomic force microscopy (AFM). Samples were studied both before and after the deposition of aluminum films to compare differences between SiC(p++)/metal and SiC(n++)/metal contact interfacial properties. Aluminum has generally been found to have good adherence to the n+ epilayer but do not form good ohmic contacts, while metal films deposited on p+ epilayers have had poor adherence but have been found to provide better ohmic character. AFM images revealed nanometer sized clusters, attributed to excess Si on the n+ epilayers, while no clusters were observed on the p+ epilayers. XPS studies of the as-prepared samples indicated that the n+ epilayers had higher concentrations of oxides which may enhance adhesion. The chemical composition and morphology is discussed and correlated to the electrical properties obtained for the various samples.

Electrical Properties of Hydrogen Intercalated Epitaxial Graphene/SiC Interface Investigated by Nanoscale Current Mapping

2015 ◽  
Vol 821-823 ◽  
pp. 929-932 ◽  
Author(s):  
Filippo Giannazzo ◽  
Stefan Hertel ◽  
Andreas Albert ◽  
Gabriele Fisichella ◽  
Antonino La Magna ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Barrier Height ◽  
Free Standing ◽  
Conductive Atomic Force Microscopy ◽  
Force Microscopy ◽  
Atomic Force ◽  
P Type ◽  
Micrometer Scale ◽  
Contact Size ◽  
Step Edges

The electrical properties of the interface between quasi free standing bilayer graphene (QFBLG) and SiC(0001) have been investigated by nanoscale resolution current measurements using conductive atomic force microscopy (CAFM). I-V analyses were carried out on Au-capped QFBLG contacts with different sizes (from 200 down to 0.5 μm) fabricated on SiC samples with different miscut angles (from on-axis to 3.5° off-axis). The extracted QFBLG/SiC Schottky barrier height (SBH) was found to depend on the contact size. SBH values ∼0.9-1 eV were obtained for large contacts, whereas a gradual increase was observed below a critical (micrometer scale) contact size (depending on the SiC miscut angle) up to values approaching ∼1.5 eV. Nanoscale resolution current mapping on bare QFLBG contacts revealed that SiC step edges and facets represent preferential current paths causing the effective SBH lowering for larger contacts. The reduced barrier height in these regions can be explained in terms of a reduced doping of QFBLG from SiC substrate at (11-20) step edges with respect to the p-type doping on the (0001) terraces.

Stable Low Resistance Ohmic Contacts To p-GaN

2001 ◽  
Vol 680 ◽  
Author(s):  
Mi-Ran Park ◽  
Wayne A. Anderson
Keyword(s):  
Contact Resistance ◽  
Photoelectron Spectroscopy ◽  
Ohmic Contacts ◽  
Depth Profiling ◽  
Force Microscopy ◽  
Low Resistance ◽  
Atomic Force ◽  
Current Voltage ◽  
Thermionic Field Emission ◽  
P Type

ABSTRACTStable and low-resistance Ohmic contacts are especially important for laser diodes where high current levels are required. Good contacts are especially difficult on p-type GaN which was the motivation for this study. The GaN was epitaxially grown on (0001) sapphire substrates by MOCVD. Resistivity of this layer was 3.5 Ohm-cm and thickness was 2 microns. After conventional cleaning followed by treatment in boiling HNO3: HCl (1:3), metallization was by thermally evaporating 40 nm Au / 60 nm Ni or 70 nm Au / 55 nm Pd. Heat treatment in O2 + N2 at various temperatures followed, with best results at 600 °C or 700 °C, respectively. Best values of the contact resistance were 1.8×10−4 Ohm-cm2 for Pd/Au and 2.65×10−4 Ohm-cm2 for Ni/Au contacts. After repetitive cycling from room temperature to 600 °C, the Ni contacts were very stable and more stable than the Pd contacts. X-ray photoelectron spectroscopy depth profiling showed the Ni contacts to be NiO followed by Au at the interface for the Ni/Au contacts whereas the Pd/Au contacts exhibited a Pd: Au solid solution. Some contacts were quenched in liquid nitrogen following sintering. These contacts were much more uniform under atomic force microscopy examination and gave a 3 times lower contact resistance with the Ni/Au design. Current-voltage-temperature analysis revealed that conduction was predominantly by thermionic field emission.

I-V and Surface Topography Study of Nanostructure Porous Silicon Layer Prepared by Electrochemical Etching

2012 ◽  
Vol 576 ◽  
pp. 519-522 ◽  
Author(s):  
Fadzilah Suhaimi Husairi ◽  
Maslihan Ain Zubaidah ◽  
Shamsul Faez M. Yusop ◽  
Rusop Mahmood Mohamad ◽  
Saifolah Abdullah
Keyword(s):  
Electrical Properties ◽  
Porous Silicon ◽  
Surface Topography ◽  
Electrochemical Etching ◽  
Silicon Layer ◽  
Porous Silicon Layer ◽  
Force Microscopy ◽  
Atomic Force ◽  
Current Voltage ◽  
P Type

This article reports on the electrical properties of porous silicon nanostructures (PSiNs) in term of its surface topography. In this study, the PsiNs samples were prepared by using different current density during the electrochemical etching of p-type silicon wafer. PSiNs has been investigated its electrical properties and resistances for different surface topography of PSiNs via current-voltage (I-V) measurement system (Keithley 2400) while its physical structural properties was investigated by using atomic force microscopy (AFM-XE100).

The Effects of Friction and Wear on PECVD Diamond Films.

1994 ◽  
Vol 339 ◽  
Author(s):  
M. L. Languell ◽  
J. L. Davidson ◽  
J. J. Wert ◽  
M. A. George ◽  
W. E. Collins ◽  
...  
Keyword(s):  
Vapor Deposition ◽  
Friction And Wear ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Nasa Lewis Research ◽  
Force Microscopy ◽  
Atomic Force ◽  
Mean Diameter ◽  
Before And After ◽  
Surface Changes

ABSTRACTThe effects of friction and wear were examined on plasma enhanced chemical vapor deposition (PECVD) diamond films deposited on tungsten substrates. The tribology of diamond on diamond was studied and the changes in surface roughness and the bearing ratio were determined before and after wear. The (111) textured heteroepitaxial films were studied morphologically by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The changes in morphology involved a transition from the large as grown diamond crystallites with a mean diameter of 10 μm to a surface with grains as small as 100 nm. The nature of the wear-modified films will be discussed regarding the possible mechanisms for the surface changes.Work partially supported by NASA Lewis Research Center grant NAG3–1430.

Effect of Electron Beam Bombarding of the Catalyst Layer on the Growth of Carbon Nanostructures by TCVD Method

2011 ◽  
Vol 264-265 ◽  
pp. 1324-1328
Author(s):  
A. Mahmoodi ◽  
M. Ghoranneviss ◽  
D. Hanifeh ◽  
K. Mehrani ◽  
M. Rahbar Zareh
Keyword(s):  
Carbon Nanotubes ◽  
Electron Beam ◽  
Carbon Nanostructures ◽  
Chemical Vapor ◽  
Catalyst Layer ◽  
Sio2 Substrate ◽  
Force Microscopy ◽  
Fe Catalyst ◽  
Atomic Force ◽  
Before And After

The growth behavior of carbon nanotubes (CNTs) grown on electron bombarded catalyst layer has been investigated in this paper. A hot cathodic electron beam facility was employed to electron bombarding of catalyst layer before stage of CNTs growth. The growth of carbon nanotubes was performed on the Fe catalyst layer with sio2 substrate in an environment of different mixed gases (H2, NH3 and C2H2) by Thermal Chemical Vapor Deposition (TCVD) system. The pretreated substrates were probed by Atomic Force Microscopy (AFM) and CNTs grown was confirmed by Raman spectroscopy. Moreover, all samples were analyzed by Scanning Electron Microscopy (SEM) before and after growth of CNTs. SEM analyzes clarified that the catalyst grains has been smaller under effect of electron beam bombardment.

scholarly journals Direct observation of chemical vapor deposited diamond films by atomic force microscopy

1992 ◽  
Vol 60 (13) ◽  
pp. 1567-1569 ◽  
Author(s):  
V. Baranauskas ◽  
M. Fukui ◽  
C. R. Rodrigues ◽  
N. Parizotto ◽  
V. J. Trava‐Airoldi
Keyword(s):  
Atomic Force Microscopy ◽  
Direct Observation ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Force Microscopy ◽  
Atomic Force ◽  
Chemical Vapor Deposited

scholarly journals Study of the Electrical Properties of Porous Silicon Prepared by Electrochemical Etching Technique

2019 ◽  
Vol 54 (5) ◽  
Author(s):  
Warood Kream Alaarage ◽  
Luma Hafedh Abed Oneiza ◽  
Mohanad Ghulam Murad Alzubaidi
Keyword(s):  
Electrical Properties ◽  
Porous Silicon ◽  
Ideality Factor ◽  
Thermal Emission ◽  
Electrochemical Etching ◽  
Point Of View ◽  
Etching Technique ◽  
Force Microscopy ◽  
Atomic Force ◽  
P Type

In our work, a P-type porous silicon (PSi) with orientation (100) have been prepared using the chemical etching method; the goal is to study the electrical properties of PSi samples prepared with completely different etching current (7, 9, 11 and 13) mA and glued for (15 min) anodization time. Depending on the atomic force microscopy (AFM) investigation, we notice the roughness of Si surface increases with increasing etching current because of increases within the dimension (diameter) of surface pits. The electrical and optoelectronic properties of prepared PSi, specifically capacitance-voltage (C-V), current-voltage (I-V), responsivity and detectivity, are analyzed. It had been found that electrical characteristics of porous Si samples measured in dark (Id) and below illumination (IPh) will be fitted well by the equations of thermal emission. From this point of view, Schottky barrier height (ɸB) and ideality factor (n) of made-up photodetectors were calculated. We tended to determine from I-V characteristics of a dark, and illuminations that the pass current through the PSi layer reduced by increasing the etching current, as a result of increasing the electrical resistance of PSi layer and therefore the optimum value of ideality factor is (2.7), whereas from C-V characteristic we determined that in-built potential accumulated with increasing etching current. The results show that there are clear results for better performance of photodetectors.

scholarly journals Determination of PMMA Residues on a Chemical-Vapor-Deposited Monolayer of Graphene by Neutron Reflection and Atomic Force Microscopy

Langmuir ◽  
2018 ◽  
Vol 34 (5) ◽  
pp. 1827-1833 ◽  
Author(s):  
Ruiheng Li ◽  
Zongyi Li ◽  
Elias Pambou ◽  
Philipp Gutfreund ◽  
Thomas A. Waigh ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Chemical Vapor ◽  
Neutron Reflection ◽  
Force Microscopy ◽  
Atomic Force ◽  
Chemical Vapor Deposited

scholarly journals Nanotribological response of a-C:H coated metallic biomaterials: the cases of stainless steel, titanium, and niobium

2018 ◽  
Vol 16 (4) ◽  
pp. 230-240
Author(s):  
Konstantinos Kapnisis ◽  
Marios Constantinou ◽  
Maria Kyrkou ◽  
Petros Nikolaou ◽  
Andreas Anayiotos ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Chemical Vapor ◽  
Scratch Resistance ◽  
Force Microscopy ◽  
Metallic Biomaterials ◽  
Atomic Force ◽  
Wear And Corrosion ◽  
Metal Plates ◽  
Before And After ◽  
Tribomechanical Characteristics

Background Wear and corrosion have been identified as two of the major forms of medical implant failures. This study aims to improve the surface, protective and tribological characteristics of bare metals used for medical implants, so as to improve scratch resistance and increase lifetime. Methods Hydrogenated amorphous carbon (a-C:H) films were deposited, using plasma enhanced chemical vapor deposition (PECVD), on stainless steel (SS), titanium (Ti) and niobium (Nb) metal plates. Nanomechanical and nanotribological responses were investigated before and after a-C:H deposition. Film thickness and density were quantified through X-ray reflectivity, and surface morphology before and after deposition were measured using atomic force microscopy, whereas the tribomechanical characteristics were probed using instrumented indentation. Results and conclusions Films of approximately 40 nm in thickness and density of 1.7 g/cm3 were deposited. The a-C:H films reduce the roughness and coefficient of friction while improving the tribomechanical response compared with bare metals for Ti, SS and Nb plates. The very good tribomechanical properties of a-C:H make it a promising candidate material for protective coating on metallic implants.

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