The influence of oxide and adsorbates on the nanomechanical response of silicon surfaces

2000 ◽  
Vol 15 (2) ◽  
pp. 546-553 ◽  
Author(s):  
S. A. Syed Asif ◽  
K. J. Wahl ◽  
R. J. Colton
Keyword(s):  
Oxide Layer ◽  
Mechanical Response ◽  
Surface Preparation ◽  
Oxide Thickness ◽  
Silicon Surfaces ◽  
Depth Sensing ◽  
Hydrophilic Surfaces ◽  
Surface Oxides ◽  
Tip Radius ◽  
Substrate Influence

In this article we report the influence of surface oxides and relative humidity on the nanomechanical response of hydrophobic and hydrophilic Si surfaces. Depth-sensing nanoindentation combined with force modulation enabled measurement of surface forces, surface energy, and interaction stiffness prior to contact. Several regimes of contact were investigated: pre-contact, apparent contact, elastic contact, and elasto-plastic contact. Both humidity and surface preparation influenced the surface mechanical properties in the pre- and apparent-contact regimes. Meniscus formation was observed for both hydrophobic and hydrophilic surfaces at high humidity. Influence of humidity was much less pronounced on hydrophobic surfaces and was fully reversible. In the elastic and elasto-plastic regimes, the mechanical response was dependent on oxide layer thickness. Irreversibility at small loads (300 nN) was due to the deformation of the surface oxide. Above 1 μN, the deformation was elastic until the mean contact pressure reached 11 GPa, whereby Si underwent a pressure-induced phase transformation resulting in oxide layer pop-in and breakthrough. The critical load required for pop-in was dependent on oxide thickness and tip radius. For thicker oxide layers, substrate influence was reduced and plastic deformation occurred within the oxide film itself without pop-in. Elastic modulus and hardness of both the oxide layer and Si substrate were measured quantitatively for depths <5 nm.

Determination of Nano Fluctuations in Surface Oxides of GaSb With Br-IBAE

2003 ◽  
Vol 786 ◽  
Author(s):  
K. Krishnaswami ◽  
B. Krejca ◽  
S.R. Vangala ◽  
C. Santeufemio ◽  
L.P. Allen ◽  
...  
Keyword(s):  
Oxide Layer ◽  
Ion Beam ◽  
Surface Preparation ◽  
Etch Depth ◽  
Oxide Surface ◽  
Material System ◽  
Oxide Interface ◽  
Average Roughness ◽  
Oxide Layers ◽  
Surface Oxides

ABSTRACTHigh-quality substrates with thin uniform oxide layers are critical to the development of low-power epitaxy-based GaSb electronic and electro-optic devices. In this material system, the thickness and elemental composition of the oxide layers are a strong function of the surface preparation method. Here, a figure of merit for quantifying the thickness and thickness variations of an oxide layer on GaSb has been developed using bromine ion beam assisted etching (Br-IBAE). Furthermore, the overall thickness and composition of the oxide determines the etch depth for a fixed set of Br-IBAE parameters. The etch rate in GaSb was determined to be ∼395nm/min and that of its surface oxides was measured to be between 1.86 to 4.2nm/min. Hence, due to the difference in etch rates, nano fluctuations of the oxide thickness at the oxide surface and at the substrate/oxide interface, result in amplified roughness fluctuations in the etched GaSb substrate. The average roughness of Br-IBAE etched surfaces is used as figures of merit to quantify the uniformity and smoothness of the oxide layer. To demonstrate this, GaSb surfaces with various oxide layers and thicknesses were identically etched and their surface roughness measured using atomic force microscopy (AFM). This novel technique can generally be extended to a number of material systems.

Correlation Between the Tunnelling Oxide and I-V Curves of MIS Photodiodes

2003 ◽  
Vol 762 ◽  
Author(s):  
H. Águas ◽  
L. Pereira ◽  
A. Goullet ◽  
R. Silva ◽  
E. Fortunato ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Oxide Layer ◽  
Spectroscopic Ellipsometry ◽  
Chemical Deposition ◽  
Oxide Thickness ◽  
Electrical Performance ◽  
Signal To Noise ◽  
Rectification Factor ◽  
Mis Devices ◽  
The Ideal

AbstractIn this work we present results of a study performed on MIS diodes with the following structure: substrate (glass) / Cr (2000Å) / a-Si:H n+ (400Å) / a-Si:H i (5500Å) / oxide (0-40Å) / Au (100Å) to determine the influence of the oxide passivation layer grown by different techniques on the electrical performance of MIS devices. The results achieved show that the diodes with oxides grown using hydrogen peroxide present higher rectification factor (2×106)and signal to noise (S/N) ratio (1×107 at -1V) than the diodes with oxides obtained by the evaporation of SiO2, or by the chemical deposition of SiO2 by plasma of HMDSO (hexamethyldisiloxane), but in the case of deposited oxides, the breakdown voltage is higher, 30V instead of 3-10 V for grown oxides. The ideal oxide thickness, determined by spectroscopic ellipsometry, is dependent on the method used to grow the oxide layer and is in the range between 6 and 20 Å. The reason for this variation is related to the degree of compactation of the oxide produced, which is not relevant for applications of the diodes in the range of ± 1V, but is relevant when high breakdown voltages are required.

WETTING BEHAVIOR IN ULTRASONIC VIBRATION-ASSISTED BRAZING OF ALUMINUM TO GRAPHITE USING Sn-Ag-Ti ACTIVE SOLDER

2015 ◽  
Vol 22 (03) ◽  
pp. 1550035 ◽  
Author(s):  
WEI-YUAN YU ◽  
SEN-HUI LIU ◽  
XIN-YA LIU ◽  
JIA-LIN SHAO ◽  
MIN-PEN LIU
Keyword(s):  
Oxide Layer ◽  
Ultrasonic Vibration ◽  
Pure Aluminum ◽  
Decomposition Temperature ◽  
Ultrasonic Waves ◽  
Atmospheric Conditions ◽  
Liquid Solder ◽  
Ambient Conditions ◽  
Composite Oxides ◽  
Surface Oxides

In this study, Sn - Ag - Ti ternary alloy has been used as the active solder to braze pure aluminum and graphite in atmospheric conditions using ultrasonic vibration as an aid. The authors studied the formation, composition and decomposition temperature of the surface oxides of the active solder under atmospheric conditions. In addition, the wettability of Sn -5 Ag -8 Ti active solder on the surface of pure aluminum and graphite has also been studied. The results showed that the major components presented in the surface oxides formed on the Sn -5 Ag -8 Ti active solder under ambient conditions are TiO , TiO 2, Ti 2 O 3, Ti 3 O 5 and SnO 2. Apart from AgO and Ag 2 O 2, which can be decomposed at the brazing temperature (773 K), other oxides will not be decomposed. The oxide layer comprises composite oxides and it forms a compact layer with a certain thickness to enclose the melted solder, which will prevent the liquid solder from wetting the base metals at the brazing temperature. After ultrasonic vibration, the oxide layer was destroyed and the liquid solder was able to wet and spread out around the base materials. Furthermore, better wettability of the active solder was observed on the surface of graphite and pure aluminum at the brazing temperature of 773–823 K using ultrasonic waves. The ultrasonic wave acts as the dominant driving factor which promotes the wetting and spreading of the liquid solder on the surface of graphite and aluminum to achieve a stable and reliable brazed joint.

Material Property of a Passive Oxide Formed on Alloy 600

2007 ◽  
Vol 26-28 ◽  
pp. 937-940 ◽  
Author(s):  
Dong Jin Kim ◽  
Hyuk Chul Kwon ◽  
Seong Sik Hwang ◽  
Hong Pyo Kim
Keyword(s):  
Corrosion Resistance ◽  
Oxide Layer ◽  
Passive Film ◽  
Electrochemical Impedance ◽  
Oxide Films ◽  
Oxide Thickness ◽  
Solution Temperature ◽  
Alloy 600 ◽  
Pressurized Water ◽  
Electrochemical Behaviors

Alloy 600 is used as a material for a steam generator tubing in pressurized water reactors(PWR) due to its high corrosion resistance under a PWR environment. In spite of its corrosion resistance, a stress corrosion cracking(SCC) has occurred on the primary side as well as the secondary side of a tubing. It is known that a SCC is related to the electrochemical behaviors of an anodic dissolution and a passivation of a bare surface of metals and alloys. Therefore in the present work, the passive oxide films on Alloy 600 have been investigated as a function of the solution temperature by using a potentiodynamic polarization, electrochemical impedance spectroscopy and a TEM, equipped with EDS. Moreover the semiconductive property was evaluated by using the Mott-Schottky relation. It was found that the passivity depends on the chemical composition and the densification of the oxide film rather than the oxide thickness. As the solution temperature of 0.5M H3BO3 increased, the thickness of the passive film increased but the oxide resistance of the passive film was decreased, indicating that the measured current in the passive region of the potentiodynamic curve is closely related to the stability of the passive film rather than the oxide thickness. It was found that the oxide films were composed of an outer oxide layer with a lower resistance and an inner oxide layer with a relatively higher resistance. From the Mott-Schottky relation, the oxide formed at 300oC showed a p-type semiconductor property unlike the n-type oxide films up to 250oC.

Effect of the Field Oxidation Process on the Electrical Characteristics of 6500V 4H-SiC JBS Diodes

2020 ◽  
Vol 1014 ◽  
pp. 144-148
Author(s):  
Ling Sang ◽  
Jing Hua Xia ◽  
Liang Tian ◽  
Fei Yang ◽  
Rui Jin ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Oxide Layer ◽  
Vapor Deposition ◽  
Oxidation Process ◽  
Chemical Vapor ◽  
Oxide Thickness ◽  
Electrical Characteristics ◽  
Field Plate ◽  
Plate Length ◽  
Field Oxide

The effect of the field oxidation process on the electrical characteristics of 6500V 4H-SiC JBS diodes is studied. The oxide thickness and field plate length have an effect on the reverse breakdown voltage of the SiC JBS diode. According the simulation results, we choose the optimal thickness of the oxide layer and field plate length of the SiC JBS diode. Two different field oxide deposition processes, which are plasma enhanced chemical vapor deposition (PECVD) and low pressure chemical vapor deposition (LPCVD), are compared in our paper. When the reverse voltage is 6600V, the reverse leakage current of SiC JBS diodes with the field oxide layer obtained by LPCVD process is 0.7 μA, which is 60% lower than that of PECVD process. When the forward current is 25 A, the forward voltage of SiC JBS diodes with the field oxide layer obtained by LPCVD process is 3.75 V, which is 10% higher than that of PECVD process. There should be a trade-off between the forward and reverse characteristics in the actual high power and high temperature applications.

A mechanistic model for oxide growth and dissolution during corrosion of Cr-containing alloys

2015 ◽  
Vol 180 ◽  
pp. 113-135 ◽  
Author(s):  
M. Momeni ◽  
J. C. Wren
Keyword(s):  
Metal Oxide ◽  
Oxide Layer ◽  
Metal Cation ◽  
Corrosion Behaviour ◽  
Mechanistic Model ◽  
Potential Drop ◽  
Oxide Thickness ◽  
Oxide Growth ◽  
Metal Oxidation ◽  
Charge Balance

We have developed a corrosion model that can predict metal oxide growth and dissolution rates as a function of time for a range of solution conditions. Our model considers electrochemical reactions at the metal/oxide and oxide/solution interfaces, and the metal cation flux from the metal to the solution phase through a growing oxide layer, and formulates the key processes using classical chemical reaction rate or flux equations. The model imposes mass and charge balance and hence, is labeled as the Mass Charge Balance (MCB) model. Mass and charge balance dictate that at any given time the oxidation (or metal cation) flux must be equal to the sum of the oxide growth flux and the dissolution flux. For each redox reaction leading to the formation of a specific oxide, the metal oxidation flux is formulated using a modified Butler–Volmer equation with an oxide-thickness-dependent effective overpotential. The oxide growth and dissolution fluxes have a first-order dependence on the metal cation flux. The rate constant for oxide formation also follows an Arrhenius dependence on the potential drop across the oxide layer and hence decreases exponentially with oxide thickness. This model is able to predict the time-dependent potentiostatic corrosion behaviour of both pure iron, and Co–Cr and Fe–Ni–Cr alloys.

Indentation-induced deformation at ultramicroscopic and macroscopic contacts

2004 ◽  
Vol 19 (1) ◽  
pp. 124-130 ◽  
Author(s):  
Jeremy Thurn ◽  
Robert F. Cook
Keyword(s):  
Plastic Deformation ◽  
Soda Lime ◽  
Soda Lime Glass ◽  
Depth Sensing ◽  
Paraboloid Of Revolution ◽  
Loading And Unloading ◽  
Load Displacement ◽  
Elastic And Plastic Deformation ◽  
Tip Radius ◽  
Unloading Stiffness

Depth-sensing indentation at ultramicroscopic and macroscopic contacts (“nanoindentation” and “macroindentation,” respectively) was performed on four brittle materials (soda-lime glass, alumina titanium carbide, sapphire, and silicon) and the resulting load–displacement traces examined to provide insight to the elastic and plastic deformation scaling with contact size. The load–displacement traces are examined in terms of the unloading stiffness, the energies deposited during loading and recovered on unloading, and the effect of the indenter tip radius on the loading curve. The results of the analyses show that the elastic and plastic deformation during loading and unloading is invariant with the scale of the contact, and the unloading curve is best described by neither a conical tip nor a paraboloid of revolution, but of some compromise.

Simplified Area Function for Sharp Indenter Tips in Depth-sensing Indentation

2002 ◽  
Vol 17 (5) ◽  
pp. 1143-1146 ◽  
Author(s):  
Jeremy Thurn ◽  
Robert F. Cook
Keyword(s):  
Cone Angle ◽  
Indentation Load ◽  
Depth Sensing ◽  
Area Function ◽  
Eden Prairie ◽  
Two Parameters ◽  
Tip Radius ◽  
Hardness Values ◽  
Effective Cone ◽  
Two Parameter

A two-parameter “area function” characterizing the depth-dependent projected area of an indenter was introduced and applied to a Berkovich tip. The two parameters have physical meaning, corresponding to the effective tip radius and effective cone angle. The indenter tip was calibrated on a commercial load-controlled Nano Indentert® XP (MTS Systems Corp., Eden Prairie, MN). All calibrations were carried out using the procedure of Oliver and Pharr [J. Mater. Res. 7, 1564 (1992)] using several homogeneous materials. Plane-strain modulus and hardness values deconvoluted from indentation load–displacement traces using the calibrated two-parameter area function compared well with the values determined using the empirical eight-parameter area function of Oliver and Pharr.

Modelling of Corrosion Induced Stresses during Zircaloy-4 Oxidation in Air

2008 ◽  
Vol 595-598 ◽  
pp. 419-427 ◽  
Author(s):  
Vincent Busser ◽  
Jean Desquines ◽  
Stéphanie Fouquet ◽  
Marie Christine Baietto ◽  
Jean Paul Mardon
Keyword(s):  
Oxide Layer ◽  
Research Work ◽  
Oxide Thickness ◽  
Stress Profile ◽  
Oxide Growth ◽  
Large Set ◽  
Transient Experiments ◽  
Cracking Mechanisms ◽  
Oxidation In Air ◽  
Good Agreement

In the frame of its research work on nuclear fuel safety, the French “Institut de Radioprotection et de Sûreté Nucléaire” (IRSN) has highlighted the importance of cladding tube oxidation on its thermomechanical behavior. The occurrence of radial cracking and spallation has been observed as the main mechanisms for the zirconia layer degradation during transient experiments. A study of these two mechanisms has been jointly launched by IRSN and Areva-NP. Thus laboratory air oxidations of fully recrystallized or stress-relieved low-tin Zircaloy-4 cladding tubes have been performed. Representative oxide layer thicknesses varying from 10 to 100 0m have been obtained. SEM micrographs of the obtained oxidised samples show that short circumferential cracks are periodically distributed in the oxide thickness. For specimens with oxide film thickness greater than 30 0m, radial cracks are initiated from the outer surface of the oxide layer and propagated radially. Veins characterised by the lack of circumferentially orientated crack are evidenced. All these phenomena are mainly linked to high compressive stress levels in the zirconia layer. A model describing the stress evolution in the oxide and in the cladding has been developed. This model takes into account the influence of elasticity, cladding creep, oxide growth and thermal expansion. Deflection tests data [15] are used to calibrate the oxide growth modelling. The model enables the evaluation of strain or stress profile in the oxide layer and in the base metal. Numerical results are in good agreement with a large set of axial and circumferential strains measurements. Further a better understanding of cracking mechanisms is achieved considering the good agreement between experimental and numerical analysis.

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