摘要:

Spherical targets can be levitated on beams of Ar or other gas atoms. This is an especially useful technique for supporting microspheres during plasma coating and processing. Measurements of gas flow and pressure indicate that the levitation device operates in the regime of Knudsen’s flow. This device is currently being used in the development of future generation laser targets.

ISSN:0022-5355    

DOI:10.1116/1.571345

出版商:American Vacuum Society    

年代:1982

数据来源: AIP

摘要:

A molecular beam source for deposition of high vapor pressure materials in MBE systems is described. The source consists of a collimating effusion cell of original design which is heated by a temperature‐controlled Radak II oven (Luxel Corporation). Construction details of the source are given along with calibration and performance data.

ISSN:0022-5355    

DOI:10.1116/1.571346

出版商:American Vacuum Society    

年代:1982

数据来源: AIP

摘要:

We report our operational experiences with a gallium phosphide source of P2vapor in the MBE growth of GaP. The use of a P2source results in much more favorable vacuum characteristics than the use of P4, as generated by an elemental phosphorus source, introducing no complications compared to the growth of arsenides. The phosphorus background pressure during growth is actually lower than the background pressure present during GaAs growth using an elemental arsenic As4source, for comparable flux rates. The few P4molecules that do form by association of P2condense as white phosphorus on the cryobaffles and re‐evaporate upon warmup. However, the pressure peaks at a value no higher than the background pressure during growth. Furthermore, the bakeout pressures are not significantly higher than those obtained using arsenic only. The P2beam generated by the GaP source contains less Ga than one might expect from equilibrium vapor pressure considerations, thus greatly facilitating the independent control of Ga and P2fluxes.

ISSN:0022-5355    

DOI:10.1116/1.571348

出版商:American Vacuum Society    

年代:1982

数据来源: AIP

摘要:

ZnO films have been prepared by rf sputtering a Zn target in a planar magnetron system with controlled Ar/O2gas mixtures. The films were deposited on unheated glass substrates which were either stationary in front of the target or in constant motion. Both the system pressure and plasma impedance changed when an oxide layer formed on the target surface. This occurred at an oxygen flow rate which increased almost linearly with rf power; at 500 W, the required flow rate was 9 ml/min and the pressure increased from 0.1 to 1.2 Pa due to the reduced oxygen gettering. High resistance ZnO films were deposited at oxygen flow rates above this threshold value. The target self‐bias voltage increased by 30 V at this value; it is affected by both the system pressure and the power. The deposition rate increased linearly with power at approximately 0.03 (μm/min)/(W/cm2) which appears to be typical of sputtering from a ZnO layer or target. For continuous substrate motion, the average rate was approximately 7% of this value. All the films were polycrystalline ZnO with a preferred orientation, thecaxis of the hexagonal structure being within a small angle of the substrate normal; this orientation was improved by motion of the substrate past the target. Films deposited at pressures of approximately 0.4 Pa had a large internal stress, as revealed both by substrate bending and x‐ray measurements. Increasing the pressure to 4.7 Pa decreased the stress by an order of magnitude. SEM analysis showed that this was associated with the development of a columnar structure. The refractive indices obtained from guided wave measurements were 1.940±0.006 and 1.962±0.003, which correspond to 97% of the single crystal values. The resistivity measured normal to the film plane was greater than 107Ω cm. The changes in film stress and structure are similar to effects in metal films. The electromechanical coupling coefficients obtained from SAW measurements are approximately half the best reported value.

ISSN:0022-5355    

DOI:10.1116/1.571350

出版商:American Vacuum Society    

年代:1982

数据来源: AIP

摘要:

A significant improvement of the lateral uniformity of thermally formed Ni2Si layers has been observed after low‐dose (1013∠3×1014ion/cm2) Xe irradiation of an As‐deposited Ni film. Measurements have also been made on samples that contained a thin impurity layer formed intentionally between the silicon substrate and the evaporated nickel film. The impurity layer was thick enough to prevent thermal silicide formation in unirradiated samples, but in irradiated samples, the silicide formation was not prevented. Similar results were obtained for As implantations. We attribute this effect to ion mixing of the interfacial layer. These results demonstrate that a low‐dose irradiation can render the process of silicide formation by thermal annealing more tolerant to interfacial impurities. The concept is of potential significance to VLSI technology.

ISSN:0022-5355    

DOI:10.1116/1.571353

出版商:American Vacuum Society    

年代:1982

数据来源: AIP

摘要:

The fabrication and properties of a new x‐ray lithography mask are described. The mask is made of a plasma enhanced chemical vapor deposited (PCVD) silicon nitride (SiN) membrane, which is supported by a silicon frame. The PCVD SiN film, deposited on silicon substrate under appropriate conditions, has a tensile stress of about 1×108dyn/cm2, which is much lower than that of a Si3N4film prepared by conventional (pyrolytic) CVD. The strength of the PCVD SiN membrane, stretched over a silicon frame, is as high as that of a Si3N4/SiO2/Si3N4sandwich structure membrane, and is much higher than that of a conventional CVD Si3N4membrane. The PCVD SiN film with low stress realizes a low distortion x‐ray mask substrate which is expected to be applied to very fine pattern lithography.

ISSN:0022-5355    

DOI:10.1116/1.571355

出版商:American Vacuum Society    

年代:1982

数据来源: AIP

摘要:

To investigate the total emission characteristics of single‐crystal LaB6cathodes, the dependence of brightness and emittance (the product of crossover size and beam divergence) on cathode tip curvature were measured. The smaller the radius of the tip curvature and the lower the tip temperature becomes, the lower the emission current at which angular emission anisotropy due to the lattice structure of LaB6crystal appears. The emission of 〈110〉 LaB6cathodes was found to be more affected by lattice structure than that of 〈110〉 LaB6cathodes. To obtain a uniform distribution beam it is more advantageous to use 〈100〉 LaB6cathodes than 〈110〉. Uniform angular emission were obtained with a 〈100〉 LaB6cathode of 100 μm tip radius even at an emission current of 700 μA and a tip temperature of 1500 °C. Under these conditions, the measured brightness and emittance were 3.9×105A/cm2 sr and 61 μm mrad, respectively.

ISSN:0022-5355    

DOI:10.1116/1.571357

出版商:American Vacuum Society    

年代:1982

数据来源: AIP

摘要:

The intensity profiles for near normal specular and normal incident nonspecular LEED beams for the three low‐index surfaces (100), (110), and (111) of aluminum have been measured as a function of temperature. From the decrease in the intensities the effective Debye temperature has been found as a function of peak energy. The mean square surface normal atomic displacements relative to the bulk are compared with calculations from the Joneset al. model. The experimentally determined ratios at zero energy are 3.6 for the (100), 4.1 for the (111), and 8.0 for the (110) surface. Theoretical calculations of the Debye temperature as a function of energy from these values agree reasonably well with experimental measurements. Electron attenuation for normal penetration into the surface for the three crystallographic planes has been determined in terms of the incident electron energy. The values are α(100)= 0.16 E0.25, α(110)= 0.12 E0.26, and α(111)= 0.20 E0.22, where α is defined as the ratio of the diffraction amplitudes from successive layers in the crystal. The shift of the peaks towards lower energy is linear over a wide temperature range and has been interpreted in terms of an increase in the surface thermal expansion which amounts to several times the bulk value. This is qualitatively supported by interplanar and interrow determinations at different temperatures.

ISSN:0022-5355    

DOI:10.1116/1.571358

出版商:American Vacuum Society    

年代:1982

数据来源: AIP

摘要:

The diamond surface undergoes a transformation in its electronic structure by a vacuum anneal ∠900 °C. The transformation is characterized by the appearance of a feature in the band gap region of the energy loss spectrum. The kinetics of the transformation on the (110) surface have been studied by observing the growth of this feature with time and temperature. It is found that the transformation is consistent with first order kinetics with an activation energy of 4.8 eV. It is also found that the band gap feature could be removed by exposing the transformed surface to excited hydrogen. These results are consistent with the polished diamond (110) surface being covered with hydrogen which removes the band gap states and can be thermally desorbed at ∠900 °C.

ISSN:0022-5355    

DOI:10.1116/1.571359

出版商:American Vacuum Society    

年代:1982

数据来源: AIP

摘要:

The total ESD cross section from an α layer of carbon monoxide adsorbed on the (110) face of tungsten has been measured as a function of the electron bombarding energy. A clear peak at 9 eV, which should also appear in electron energy loss spectroscopy (ELS), is here reported for the first time. An attempt is made at correlating this peak with the electronic structure of the adsorbed molecule, concluding that it stems from 5σ→2π* transitions.

ISSN:0022-5355    

DOI:10.1116/1.571360

出版商:American Vacuum Society    

年代:1982

数据来源: AIP