Asymptotic step profiles from a nonlinear growth equation for vicinal surfaces

We study a recently proposed nonlinear evolution equation describing the collective step meander on a vicinal surface subject to the Bales-Zangwill growth instability [O. Pierre-Louis et al., Phys. Rev. Lett. (80), 4221 (1998)]. A careful numerical analysis shows that the dynamically selected step profile consists of sloped segments, given by an inverse error function and steepening as sqrt(t), which are matched to pieces of a stationary (time-independent) solution describing the maxima and minima. The effect of smoothening by step edge diffusion is included heuristically, and a one-parameter family of evolution equations is introduced which contains relaxation by step edge diffusion and by attachment-detachment as special cases. The question of the persistence of an initially imposed meander wavelength is investigated in relation to recent experiments.Comment: 4 pages, 5 included figures. Typo in Eq.(5) corrected, section headlines added and Ref.[12] update

Competing mechanisms for step meandering in unstable growth

The meander instability of a vicinal surface growing under step flow conditions is studied within a solid-on-solid model. In the absence of edge diffusion the selected meander wavelength agrees quantitatively with the continuum linear stability analysis of Bales and Zangwill [Phys. Rev. B {\bf 41}, 4400 (1990)]. In the presence of edge diffusion a local instability mechanism related to kink rounding barriers dominates, and the meander wavelength is set by one-dimensional nucleation. The long-time behavior of the meander amplitude differs in the two cases, and disagrees with the predictions of a nonlinear step evolution equation [O. Pierre-Louis et al., Phys. Rev. Lett. {\bf 80}, 4221 (1998)]. The variation of the meander wavelength with the deposition flux and with the activation barriers for step adatom detachment and step crossing (the Ehrlich-Schwoebel barrier) is studied in detail. The interpretation of recent experiments on surfaces vicinal to Cu(100) [T. Maroutian et al., Phys. Rev. B {\bf 64}, 165401 (2001)] in the light of our results yields an estimate for the kink barrier at the close packed steps.Comment: 8 pages, 7 .eps figures. Final version. Some errors in chapter V correcte

Nonmonotonic roughness evolution in unstable growth

The roughness of vapor-deposited thin films can display a nonmonotonic dependence on film thickness, if the smoothening of the small-scale features of the substrate dominates over growth-induced roughening in the early stage of evolution. We present a detailed analysis of this phenomenon in the framework of the continuum theory of unstable homoepitaxy. Using the spherical approximation of phase ordering kinetics, the effect of nonlinearities and noise can be treated explicitly. The substrate roughness is characterized by the dimensionless parameter $Q = W_0/(k_0 a^2)$, where $W_0$ denotes the roughness amplitude, $k_0$ is the small scale cutoff wavenumber of the roughness spectrum, and $a$ is the lattice constant. Depending on $Q$, the diffusion length $l_D$ and the Ehrlich-Schwoebel length $l_{ES}$, five regimes are identified in which the position of the roughness minimum is determined by different physical mechanisms. The analytic estimates are compared by numerical simulations of the full nonlinear evolution equation.Comment: 16 pages, 6 figures, to appear on Phys. Rev.

Ursinus College Alumni Journal, February 1951

President\u27s page • Five sons and daughters of alumni members of 1954 class at Ursinus • Dr. Miller to present 10-week course on TV • Lt. Governor L. H. Wood takes Harrisburg office • 16 receive degrees on Founders\u27 Day • Dr. Jessie Greaves named distinguished daughter • York alumni show Noss film as scholarship benefit • American Magazine spotlights Isabelle Barr • Ursinus ivy at Cedar Crest • Glassmoyer resigns as journal editor • Memorable Old Timers\u27 Day enjoyed by many • New York association elects Rev. N. Alexander • Ursinus Women\u27s Club holds annual luncheon • Arvanitis to do research on heart-lung machine • Alumni plan fund benefit at Ursinus • Dr. G. E. Pfahler named to alumni presidency • Alumni prominent in church pageant • 1950-51 committees are appointed • Bomberger leads Ursinus through its early years • Sports review: Bruin Grapplers face fair season; Seedersmen off to high scoring start in 1950-51 campaign; Soccer team winless, ties alumni 2-2; Hockeyites take five, Vadner on all-college; Eleven tabs two wins, frosh play big role • Necrology • News about ourselveshttps://digitalcommons.ursinus.edu/alumnijournal/1040/thumbnail.jp

Ursinus College Alumni Journal, September 1951

President\u27s page • Dr. Harry Cochran addresses graduating class • Newcomen Society honors Ursinus • Robert Herber awarded Fulbright scholarship • Dr. Prentis to speak on Founders Day • Faculty changes 1951-52 • New stack level houses 17,000 volumes • Ilse Helfferich weds • Former student bequeaths Ursinus College $77,000 • Hood honors Mr. Noss • New Ursinus directors • Statistical report for twentieth reunion • Alumni Day resume • Class of \u2726 celebrates twenty-fifth reunion • Memorial scholarship drive totals$60,000 • 58 attend York County banquet • Alumni Athletic Association reorganized • Ursinus Women\u27s Club • Mrs. Pancoast named alumni secretary • October 27th Old Timers\u27 Day • Alumni win awards at theological seminary • Douthett kept busy despite retirement • Richard Wentzel winner in newspaper writing contest • Bunny wins again • York alumni take part in dedication ceremonies • Teru Hayashi develops an artificial muscle • Necrology • Sports review: Young replaces Landes on Bears coaching staff; Coeds end softball season undefeated; Football prospects for \u2751 season appear bright; Women\u27s tennis team wins five, loses three; Varsity baseball closes with 7 wins, 10 losses; New track records set; Miller\u27s netmen close season with 7-2 record • Student life at Ursinus in the late 1800s • News about ourselveshttps://digitalcommons.ursinus.edu/alumnijournal/1042/thumbnail.jp

Ursinus College Alumni Journal, May 1951

President\u27s page • Lloyd H. Wood, \u2725, inaugurated as Pennsylvania\u27s Lt. Governor • Dr. H. A. Cochran, of Temple, to address graduating class • Ursinus to be honored by Newcomen Society • Russian DP starts new life at Ursinus • Artist to glorify queen in May Day pageant • Catalogue re-designed • Program completed for 1951 Alumni Day • Dinner held for seniors • Scholarship fund benefit proceeds total $1700 • Marjorie Trayes becomes Rutger\u27s Dean on July 1 • Crossley first reported casualty from Ursinus • Rhea D. Johnson retires • Laucks antique collection near museum proportions • Mack Trucks, Inc., head sets great 1950 record • First Ursinus faculty, courses are selected • Sports review: New candidates display promise as varsity nine posts 3-6 record; Undefeated in 3 years, Helfferich takes MAC award; Slim holdover track squad greets Gurzynski; Alumnae continue active in Philadelphia area sports; Court team winds up successful season with 10 wins in 18 games; Dr. Miller selected as new Ursinus tennis coach; Mermaids drop seven, veteran \u2752 squad sure; Top sports record goes to girls\u27 basketball team; Ursinus\u27 1910 team and the same players today • Obituary • News about ourselveshttps://digitalcommons.ursinus.edu/alumnijournal/1041/thumbnail.jp

Surface Kinetics and Generation of Different Terms in a Conservative Growth Equation

A method based on the kinetics of adatoms on a growing surface under epitaxial growth at low temperature in (1+1) dimensions is proposed to obtain a closed form of local growth equation. It can be generalized to any growth problem as long as diffusion of adatoms govern the surface morphology. The method can be easily extended to higher dimensions. The kinetic processes contributing to various terms in the growth equation (GE) are identified from the analysis of in-plane and downward hops. In particular, processes corresponding to the (h -> -h) symmetry breaking term and curvature dependent term are discussed. Consequence of these terms on the stable and unstable transition in (1+1) dimensions is analyzed. In (2+1) dimensions it is shown that an additional (h -> -h) symmetry breaking term is generated due to the in-plane curvature associated with the mound like structures. This term is independent of any diffusion barrier differences between in-plane and out of-plane migration. It is argued that terms generated in the presence of downward hops are the relevant terms in a GE. Growth equation in the closed form is obtained for various growth models introduced to capture most of the processes in experimental Molecular Beam Epitaxial growth. Effect of dissociation is also considered and is seen to have stabilizing effect on the growth. It is shown that for uphill current the GE approach fails to describe the growth since a given GE is not valid over the entire substrate.Comment: 14 pages, 7 figure

Ursinus College Alumni Journal, November 1952

President\u27s page • Dr. Clawson retired • Donald L. Helfferich Founders\u27 Day speaker • Dr. Armstrong named Dean of the college • Dr. John B. Price dies • Drexel head delivers commencement address • Ursinus welcomes new members • Ursinus opens 83rd year • Ursinus mourns the death of Dr. Brownback • Contributors to the Alumni Memorial Scholarship Fund • Alumni Day report • Roger Staiger named faculty representative • Jessie Royer Greaves celebrates 60th reunion • Attention Philadelphia regional alumni • Bunny Vosters heads Old Timers\u27 Day • Two Ursinus alumni work together at Agape • Thrygve Meeker wins research fellowship • Paul Mattis joins SKF as head of pharmacology • Kenneth Fink a national pollster • Coach Gurzynski looks over the Grizzlies • Hockey Belles open season October 10 • Baker\u27s soccer squad foresees tough season • News about ourselves • Necrologyhttps://digitalcommons.ursinus.edu/alumnijournal/1045/thumbnail.jp

A Simple Model for Anisotropic Step Growth

We consider a simple model for the growth of isolated steps on a vicinal crystal surface. It incorporates diffusion and drift of adatoms on the terrace, and strong step and kink edge barriers. Using a combination of analytic methods and Monte Carlo simulations, we study the morphology of growing steps in detail. In particular, under typical Molecular Beam Epitaxy conditions the step morphology is linearly unstable in the model and develops fingers separated by deep cracks. The vertical roughness of the step grows linearly in time, while horizontally the fingers coarsen proportional to $t^{0.33}$. We develop scaling arguments to study the saturation of the ledge morphology for a finite width and length of the terrace.Comment: 20 pages, 12 figures; [email protected]

Ursinus College Alumni Journal, Winter 1946

Dean • President\u27s page • Record enrollment in 76th year • Necrology • Dean Kline dies in 83rd year • Livingood honored • Dr. Niblo attends Episcopal convention • Music room developed • Faculty increased • Revue of sports • Seeders appointed head basketball coach • Student activities • Letters to the alumni • Old Timers\u27 Day • Alumni committees appointed • Re-education of Germany • News about ourselves • Dr. Haines: Teacher and author • News around town • Recipient of Rotary Club award • Dr. Markley completes term of service • 1946 and football • As the placement office sees us • Men\u27s basketball schedulehttps://digitalcommons.ursinus.edu/alumnijournal/1026/thumbnail.jp