摘要:

A novelinsitustress measurement technique to study the formation kinetics of multicomponent oxide thin films was developed and was applied to PbTiO3. Single phase PbTiO3thin films were formed from the reaction between films in the deposited PbO/TiO2multilayer. The film stoichiometry was accurately controlled by depositing individual layers with the required thickness. The development of film stresses associated with the formation of the product layer at the PbO/TiO2interface of the multilayers was used to monitor the growth rate of the PbTiO3layer. It was found that growth of the PbTiO3phase obeyed the parabolic law, and the effective activation energy was estimated to be 108 kJ/mole. It is believed that the mechanism of this reaction was dominated by grain boundary diffusion of the participating cations.

ISSN:0734-2101    

DOI:10.1116/1.579919

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

Stress relaxation in PbTiO3films was investigated by theinsitustress measurement technique. A simple viscous flow model was successfully used to interpret the kinetics and behavior of stress relaxation of PbTiO3thin films. The activation energy responsible for stress relaxation was estimated to be 190 kJ/mole, which was accounted for by the lattice diffusion of vacancies. A Nabarro–Herring creep model was successfully employed to correlate the relationships among the viscosity, lattice diffusion coefficient, and grain size of the PbTiO3films, and an estimate of the lattice diffusion coefficient of vacancy motion during relaxation was obtained. Also, the observed time required for complete relaxation was found to be in accord with theoretical values. Hillock formation resulting from grain boundary sliding is believed to contribute to stress relaxation in its early stage. Thereafter, grain growth resulting from lattice diffusion is believed to play a major role in the stress relaxation.

ISSN:0734-2101    

DOI:10.1116/1.579883

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

The effects of ion bombardment on multicomponent oxides, such as PbTiO3, and multilayer systems have been extensively studied by aninsitustress measurement technique. Energetic ion bombardment was found to accelerate PbTiO3formation. Both the annealing temperature and the time needed for completion of the reaction were reduced. The apparent activation energy responsible for stress relaxation was found to be 310 kJ/mole for ion‐assisted deposition (IAD) films, which is 120 kJ/mole higher than that for non‐IAD films. This was attributed to stress reduction in PbTiO3thin films resulting from ion bombardment. In addition, effects of ion bombardment on the stress of as‐deposited multilayers, on the stress development in multilayers during annealing, and on the structure–property‐processing interrelationships were also investigated.

ISSN:0734-2101    

DOI:10.1116/1.579910

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

Second harmonic microscopy has been used to quantify the surface diffusion of In on Si(111). At temperatures near 50% of the bulk melting temperature and in the coverage range 0<θ<0.7, the activation energyEdiffand pre‐exponential factorD0lie at 42±0.5 kcal/mol and 3×103±0.3cm2/s, respectively. These parameters, which are quite large, are explained semiquantitatively by reference to an adatom–vacancy model recently developed for related systems. The present work, when compared with the results of these other systems, offers significant evidence for the effects of adatom–vacancy ionization.

ISSN:0734-2101    

DOI:10.1116/1.579925

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

A study of the room‐temperature growth of ultrathin Ti films [up to 7 monolayers (ML)] on clean and atomically flat Si(111)‐(7×7) surfaces using Auger electron spectroscopy and low‐energy electron diffraction (LEED) is presented. The variations in the Auger signal due to SiL2,3VVwith binding energy of 92 eV are used to model the growth morphology of this system. These measurements indicate the growth of an initial disordered and continuous Ti film of up to 1.6 ML in thickness where the LEED pattern completely disappears and the Si Auger signal is strongly attenuated. As more Ti is deposited, this is followed by the disintegration of the continuous film and the formation of an intermixed Ti/Si film. This is evidenced by a change in the slope of the Auger signal time plot, and the reappearance of the LEED pattern. The modification in the overlayer composition for films thicker than 1.6 ML is confirmed by a change in the SiL2,3VVAuger peak that resembles the peak shape due to TiSi2.

ISSN:0734-2101    

DOI:10.1116/1.579875

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

The addition of He to N2increases significantly the deposition rate of lithium phosphorus oxynitride thin films by radio frequency magnetron sputtering of Li3PO4targets. From the correlation with the optical emission intensity, the enhanced rate is attributed to an increase in the N+2ion concentration in the plasma due to Penning ionization. The ionic conductivity of the films deposited at higher rates in He+20% N2compares favorably with that of films deposited at lower rates in pure N2.

ISSN:0734-2101    

DOI:10.1116/1.579876

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

X‐ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) were used to identify gas reaction layers and tribochemical films formed during reciprocating sliding tests in an ultrahigh vacuum (UHV) tribometer. Tests were performed on UHV cleaned SiC pins and Mo flats during or after exposure to SO2, O2, or H2S gas at pressures around 40 Pa. XPS identified the gas reaction layers on Mo to be chemisorbed MoS2and/or MoO2phases less than 1 nm thick. AES of Mo wear tracks showed tribochemical films similar in composition to, but thicker than, the reaction layers. AES of SiC wear scars in all three gases indicated tribochemical films containing Si oxide and/or Si sulfide and possibly graphite. In addition, transfer films of Mo oxysulfide and Mo oxide were found in SO2and O2tests, respectively, but no transfer films were detected in H2S tests. Thermochemical calculations of stable reaction products of the gas–solid reactions were in good agreement with the phases inferred from XPS and AES. An explanation for the agreement between thermochemical predictions and tribochemical results is given.

ISSN:0734-2101    

DOI:10.1116/1.579877

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

Thin films of superhard nanocrystalline nc‐W2N/amorphousa‐Si3N4composite have been prepared by plasma chemical vapor deposition at temperatures in the range, 500–550 °C. Maximum hardness of 5200 kg/mm2(about 51 GPa) and elastic modulus of ≥500 GPa is reached at a silicon content of 7–8 at. %. During the indentation experiment the material shows a large elastic recovery of 80%, which compares favorably with those of harda‐C:H (hardness only about 2000 kg/mm2). The results are similar to those recently obtained with nc‐TiN/a‐Si3N4and thus support our concept for the design of novel superhard composite materials with a variety of transition metal nitrides. The question of the upper limit of the strength of these materials is addressed and discussed.

ISSN:0734-2101    

DOI:10.1116/1.579878

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

Contact potential difference (CPD) experiments were conducted by the vibrating probe (Kelvin) method on humidity‐exposed hard disk drive surfaces. The measurements were made at various locations along the circumference of a wear track caused by the sliding contact with a spherical silicon pin, operated in a pin‐on‐disk configuration. The load on the pin, rotational speed of the disk, and the humidity were controlled. The CPD signals varied along the wear track and the magnitude of the CPD change increased with the load from 29 to 98 mN at a fixed relative humidity. The CPD signals also increased linearly with relative humidity ranging from 30% to 70% as the normal load was fixed at 29 and 49 mN. The CPD signal appears to saturate at a load of 98 mN where the relative humidity is 50% and higher.

ISSN:0734-2101    

DOI:10.1116/1.579879

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

This article reports on the structure and mechanical properties of CNxthin films deposited by unbalanced reactive magnetron sputtering of C in N2discharges. The films were grown on Si(001) substrates kept at temperatures (Ts) between 150 and 600 °C. Depending onTs, the films contained between 15 and 26 at. % N. X‐ray photoelectron spectroscopy of samples typically showed two peaks in the C 1score level spectrum (centered at 284.5 and 286.2 eV) and two peaks in the N 1score level spectrum (centered at 398.4 and 400.3 eV). This indicates that there are two types of C–N bonds where N is bonded to bothsp2‐ andsp3‐coordinated C atoms in the as‐deposited films. Transmission electron microscopy showed that the films produced in the temperature range 200≤Ts≤600 °C had a highly textured, turbostraticlike structure with thecaxis in the plane of the film. The basal planes in this structure were found to be buckled and bent due to incorporation of N in substitutional sites. By contrast, films produced atTs=150 °C were generally amorphous, but contained ∼3 nm diamond clusters. The mechanical properties were evaluated in nanoindentation experiments. Load versus deflection curves showed that the 0.3 μm films grown atTs≥200 °C had very high elastic recoveries with values up to 85% of the total indentation displacement. Analyses of the shapes of the load versus deflection curves, using a modeling approach that takes into account the elastic and plastic properties of both the film and the substrate, indicate that the contact deformation of the CNxfilms was predominantly elastic and the films’ hardness values were estimated to be in the range 40–60 GPa. The high hardness and elasticity are proposed to be due to the buckling of the graphitic basal planes, resulting in a structure where thesp2‐bonded basal planes are terminated with N bonded tosp3‐hybridized carbon atoms that result in a dense, three dimensional, covalently bonded network.

ISSN:0734-2101    

DOI:10.1116/1.579880

出版商:American Vacuum Society    

年代:1996

数据来源: AIP