摘要:

The interaction of atomic hydrogen with the (110) face of InP, prepared by cleavage under ultrahigh vacuum, has been studied by Auger electron spectroscopy, electron energy‐loss spectroscopy, low‐energy electron diffraction, and photoemission yield spectroscopy. The interaction occurs in two stages: first, an adsorption of H, then a decomposition of the substrate. The adsorption stage is characterized by the covalent bonding of, most likely, one H atom per surface unit cell which induces a change in the surface reconstruction of the substrate, the surface unit mesh remaining 1×1. A hydrogen‐induced surface state band, about 0.26 eV wide, is observed around 0.06 eV below the valence‐band edge. Upon H adsorption, the Fermi level gets pinned in the gap at about 0.4 eV below the conduction‐band edge on bothn‐ andp‐type samples, while the ionization energy decreases, the decrease reaching 0.35 eV at saturation.

ISSN:0734-2101    

DOI:10.1116/1.574979

出版商:American Vacuum Society    

年代:1988

数据来源: AIP

摘要:

Auger electron spectroscopy, electron energy‐loss spectroscopy, low‐energy electron diffraction, and photoemission yield spectroscopy have been used to study the interaction of atomic hydrogen with cleaved InP(110) upon heavy hydrogenation. Beyond the initial adsorption stage, the substrate dissociates into In metal and possibly two hydrogenated compounds of P, among which most likely phosphine PH3, which remain adsorbed on the surface. This interaction stage is characterized by the existence of the ‘‘black hole’’ phenomenon in photoemission yield spectroscopy, i.e., the complete disappearance of the photoemission signal at 5.3 and ∼5 eV, photon energies specific of the adsorbed species. The hydrogenated compounds desorb upon heating at 525 °C leaving a surface close to its H‐adsorbed state. From there on, the properties of the surface can by cycled by, alternately, introducing a new heavy dose of H and annealing.

ISSN:0734-2101    

DOI:10.1116/1.574980

出版商:American Vacuum Society    

年代:1988

数据来源: AIP

摘要:

To investigate quantitatively the effect of oxygen on the ion yields in secondary ion mass spectrometry (SIMS) analysis of impurities in GaAs, oxygen‐implanted GaAs crystals were prepared. Oxygen‐induced ion yield enhancement was demonstrated by the SIMS analysis of these oxygen‐implanted GaAs crystals. B, Cr, Cu, and Mn in these crystals were found to have impurity ion yields 50 times larger than those without oxygen under Ar+bombardment. The ion yield enhancement of impurities by oxygen has been interpreted by treating ion yields as a function of oxygen fraction, i.e., probability of occupying the adjacent site to the impurities by oxygen atoms. For oxygen fractions, the local thermodynamic equilibrium calculations were carried out to obtainTparameters which enable the impurity ion yields to be estimated only by ionization potentials if the oxygen fraction is given.

ISSN:0734-2101    

DOI:10.1116/1.574981

出版商:American Vacuum Society    

年代:1988

数据来源: AIP

摘要:

When a clean Zr(0001) crystal is exposed to oxygen at 82 K, the work function initially decreases by ∼250 mV for an exposure of 0.7 to 0.8 L. Annealing this surface to ∼550 K produces a further decrease in work function of ∼300 mV, and a ‘‘(2×2)‐like’’ low‐energy electron diffraction pattern is observed. The initial decrease in work function upon oxygen adsorption at 82 K is believed to be due to oxygen incorporation into the Zr lattice.

ISSN:0734-2101    

DOI:10.1116/1.574982

出版商:American Vacuum Society    

年代:1988

数据来源: AIP

摘要:

This report describes the influence of surface roughness resulting from the Mo film sputter process on oxygen profiles of the thin SiO2interlayer in an Mo/SiO2/Si structural sample. The sputter‐induced surface roughness causes expansion of oxygen profiles. The expansion increases as the Mo grain size increases. This is why the original surface roughness of an Mo film deposited on an SiO2surface is almost all proportional to Mo grain size (20–300 nm) and why the sputter‐induced surface roughness is developed by the original Mo surface roughness. The relation between sputter‐induced inexactness resulting from the Mo film sputter process and an expanded oxygen profile of the thin SiO2interlayer is obtained. The Mo grain size is controlled by postdeposition heat treatment (800–1100 °C).

ISSN:0734-2101    

DOI:10.1116/1.574983

出版商:American Vacuum Society    

年代:1988

数据来源: AIP

摘要:

Morphologies and structures of surface cones formed on polycrystalline Cu targets seeded with Mo were surveyed by means of high‐resolution electron microscopy. The sputtering of the target with a focused Ar+‐ion beam generated Cu cones having diversified configurations and crystalline states, obviously reflecting an intricate mechanism of cone evolution. Some of the cones observed were characterized by an amorphouslike structure, commonly grown at the apex areas, and Mo was never detected from coned areas. These findings strongly suggest that the role of Mo seeds was to nucleate cones, and that the direct supply of sputtered Cu atoms to the cone nucleation sites interplayed with the ion‐etching process so as to develop the nucleated cones.

ISSN:0734-2101    

DOI:10.1116/1.574984

出版商:American Vacuum Society    

年代:1988

数据来源: AIP

摘要:

The current–voltage relationship in a magnetron plasma appears to be strongly dependent on the dynamics of the sputtered particle–gas atom interaction. Large fluxes of energetic (several eV) sputtered atoms from the cathode heat the gas in the near cathode region, resulting in a significant reduction in the local gas density as a function of discharge current (and hence particle flux). This reduction in gas density results in a lower rate of ion formation, and hence a more resistive plasma. Thus, the rate of voltage increase with current in a magnetron is related to the magnitude of the gas density rarefaction, which is dependent on the cathode sputter yield, sputtered atom energy, the cross section for sputtered atom–gas collisions, the molecular velocity of the gas, and the gas density. A model has been developed which describes the observed rate of voltage increase in a magnetron as a function of this thermalization process.

ISSN:0734-2101    

DOI:10.1116/1.574985

出版商:American Vacuum Society    

年代:1988

数据来源: AIP

摘要:

A proposal for an in‐vessel movable leak sensor, called a leak test telescope, is described for leak localization inside two of the largest thermonuclear fusion devices (TFTR and JET). To improve sensitivity and source identification beyond the present state of the art, a differential sensor head employing two actively pumping collimators, a continuously rotating shutter, and a quadrupole mass spectrometer as sensor is proposed. With the use of phase‐lock signal processing this detector should be capable of detecting a leak of 1×10−6Torr l/s from a distance of 0.5 m in a typical fusion environment with backgrounds>1×10−7Torr deuterium–tritium.

ISSN:0734-2101    

DOI:10.1116/1.575433

出版商:American Vacuum Society    

年代:1988

数据来源: AIP

摘要:

Useful data on the backstreaming of vapors from oil sealed rotary pumps have been obtained by a number of workers using quartz‐crystal microbalance techniques. The interpretation of results obtained using this method is complicated by the heterogeneous nature of the pump fluids, arising mainly from degradation of oil in the pump mechanism, and by the large vapor pumping speed of the cold finger on which the quartz crystal is mounted. The work described here attempts to separate the factors involved and to quantify their effects. The results obtained support a proposed model of the vapor atmosphere of which the most significant feature is the limited production rate of degraded oil products. It is shown that the significance of backstreaming rates, measured using a cooled quartz crystal, is strongly dependent on the experimental arrangement.

ISSN:0734-2101    

DOI:10.1116/1.575434

出版商:American Vacuum Society    

年代:1988

数据来源: AIP

摘要:

Tellurium suboxide (TeOx) thin films have been obtained by rf reactive sputtering deposition by using a Te target and an Ar–O2gas mixture. Different samples were prepared by changing both the rf power (80–200 W) and the oxygen concentration in the sputtering gas. The transmissivity and the reflectivity of these films change markedly by thermal treatment at critical temperatures in the range 120–150 °C. This property makes these films suitable for optical disk recording with a low‐output power laser diode.

ISSN:0734-2101    

DOI:10.1116/1.575435

出版商:American Vacuum Society    

年代:1988

数据来源: AIP