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Nanometer Scale Patterning And Oxidation Of Silicon Surfaces With An Ultrahigh Vacuum Scanning Tunneling Microscope, J. W. Lyding, G. C. Abeln, T. -C. Shen, C. Wang, J. R. Tucker
Nanometer Scale Patterning And Oxidation Of Silicon Surfaces With An Ultrahigh Vacuum Scanning Tunneling Microscope, J. W. Lyding, G. C. Abeln, T. -C. Shen, C. Wang, J. R. Tucker
T. -C. Shen
Nanoscale patterning of the Si(100)‐2×1 monohydride surface has been achieved by using an ultrahigh vacuum (UHV) scanning tunneling microscope(STM) to selectively desorb the hydrogen passivation. Hydrogen passivation on silicon represents one of the simplest possible resist systems for nanolithography experiments. After preparing high quality H‐passivated surfaces in the UHV chamber, patterning is achieved by operating the STM in field emission. The field emitted electrons stimulate the desorption of molecular hydrogen, restoring clean Si(100)‐2×1 in the patterned area. This depassivation mechanism seems to be related to the electron kinetic energy for patterning at higher voltages and the electron current for low …
Comparison Between Calculatedand Observed F-Region Density Profiles At Jicamarca, Peru, A. J. Preble, D. N. Anderson, Bela G. Fejer, P. H. Doherty
Comparison Between Calculatedand Observed F-Region Density Profiles At Jicamarca, Peru, A. J. Preble, D. N. Anderson, Bela G. Fejer, P. H. Doherty
Bela G. Fejer
Electron density profiles and isodensity contours derived from Jicamarca incoherent scatter radar observations in Peru for October 1–2, 1970, are compared in detail with results from the Phillips Laboratory global theoretical ionospheric model. This model solves the ion continuity equation for O+ concentration through production, loss, and transport of ionization. The primary factor controlling the peak plasma density at Jicamarca is the vertical E×B drift, which drives the ionization upward during the day and downward at night. When we use the measured drift in the model, we achieve excellent results with the measured electron density profiles. We illustrate the sensitivity …
Nanoscale Patterning And Oxidation Of H-Passivated Si(100)-2x1 Surfaces With An Ultrahigh Vacuum Scanning Tunneling Microscope, J. W. Lyding, T. -C. Shen, J. S. Hubaceck, J. R. Tucker, G. C. Abeln
Nanoscale Patterning And Oxidation Of H-Passivated Si(100)-2x1 Surfaces With An Ultrahigh Vacuum Scanning Tunneling Microscope, J. W. Lyding, T. -C. Shen, J. S. Hubaceck, J. R. Tucker, G. C. Abeln
T. -C. Shen
Nanoscale patterning of the hydrogen terminated Si(100)‐2×1 surface has been achieved with an ultrahigh vacuum scanning tunneling microscope.Patterning occurs when electrons field emitted from the probe locally desorb hydrogen, converting the surface into clean silicon. Linewidths of 1 nm on a 3 nm pitch are achieved by this technique. Local chemistry is also demonstrated by the selective oxidation of the patterned areas. During oxidation, the linewidth is preserved and the surrounding H‐passivated regions remain unaffected, indicating the potential use of this technique in multistep lithography processes.
Efficient Timestamp Input And Output, Curtis Dyreson, Richard T. Snodgrass
Efficient Timestamp Input And Output, Curtis Dyreson, Richard T. Snodgrass
Curtis Dyreson
In this paper we provide efficient algorithms for converting between the internal form of a timestamp, and various external forms, principally character strings specifying Gregorian dates. We give several algorithms that explore a range of time and space tradeoffs. Unlike previous algorithms that explore a range of time and space tradeoffs. Unlike previous algorithms, those discussed here have a constant time cost over a greatly extended range of timestamp values. These algorithms are especially useful in operating systems and in database management systems.