4,132 research outputs found

    Ge growth on ion-irradiated Si self-affine fractal surfaces

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    We have carried out scanning tunneling microscopy experiments under ultrahigh vacuum condition to study the morphology of ultrathin Ge films eposited on pristine Si(100) and ion-irradiated Si(100) self-affine fractal surfaces. The pristine and the ion-irradiated Si(100) surface have roughness exponents of alpha=0.19+/-0.05 and alpha=0.82+/-0.04 respectively. These measurements were carried out on two halves of the same sample where only one half was ion-irradiated. Following deposition of a thin film of Ge (~6 A) the roughness exponents change to 0.11+/-0.04 and 0.99+/-0.06, respectively. Upon Ge deposition, while the roughness increases by more than an order of magnitude on the pristine surface, a smoothing is observed for the ion-irradiated surface. For the ion-irradiated surface the correlation length xi increases from 32 nm to 137 nm upon Ge deposition. Ge grows on Si surfaces in the Stranski-Krastanov or layer-plus-island mode where islands grow on a wetting layer of about three atomic layers. On the pristine surface the islands are predominantly of square or rectangular shape, while on the ion-irradiated surface the islands are nearly diamond shaped. Changes of adsorption behaviour of deposited atoms depending on the roughness exponent (or the fractal dimension) of the substrate surface are discussed.Comment: 5 pages, 2 figures and 1 tabl

    A Reaction Diffusion Model Of Pattern Formation In Clustering Of Adatoms On Silicon Surfaces

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    We study a reaction diffusion model which describes the formation of patterns on surfaces having defects. Through this model, the primary goal is to study the growth process of Ge on Si surface. We consider a two species reaction diffusion process where the reacting species are assumed to diffuse on the two dimensional surface with first order interconversion reaction occuring at various defect sites which we call reaction centers. Two models of defects, namely a ring defect and a point defect are considered separately. As reaction centers are assumed to be strongly localized in space, the proposed reaction-diffusion model is found to be exactly solvable. We use Green's function method to study the dynamics of reaction diffusion processes. Further we explore this model through Monte Carlo (MC) simulations to study the growth processes in the presence of a large number of defects. The first passage time statistics has been studied numerically. Copyright 2012 Author(s). This article is distributed under a Creative Commons Attribution 3.0 Unported License. [http://dx.doi.org/10.1063/1.4757592]Microelectronics Research Cente

    Path Dependence, VRIN Resource Endowments, and Managers: Towards an Integration of Resource-Based Theory and Upper Echelons Theory

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    Path dependencies associated with the firm’s evolving resource endowments lead to redundancies, which makes it sub-optimal to attain sustainable competitive advantage based on these resource bundles. In this context, managers can play a proactive role by ensuring that resource endowments continue to remain beneficial for their organizations. By suggesting such a linkage and the enabling role of managers, I provide a way to integrate core arguments of two of the foremost organizationaltheories in vogue: resource-based theory (RBT) and upper echelons theory (UET)

    Four Zero Texture Fermion Mass Matrices in SO(10) GUT

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    We attempt the integration of the phenomenologically successful four zero texture of fermion mass matrices with the renormalizable SO(10) GUT. The resulting scenario is found to be highly predictive. Firstly, we examine the phenomenological implications of a class of the lepton mass matrices with parallel texture structures and obtain interesting constraints on the parameters of the charged lepton and the neutrino mass matrices. We combine these phenomenological constraints with the constraints obtained from SO(10) GUT to reduce the number of the free parameters and to further constrain the allowed ranges of the free parameters. The solar/atmospheric mixing angles obtained in this analysis are in fairly good agreement with the data.Comment: 14 pages, 3 figures, 1 tabl

    Inquiring into Entrepreneurial Orientation: Making Progress, One Step at a Time

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    As we think through the four papers that comprise this special issue, we cannot help but be elated at the progress made by entrepreneurial orientation (EO) scholarship over the past few decades. Indeed, it seems safe to contend that EO defies the description of entrepreneurship research as a “hodgepodge” (Shane & Venkataraman, 2000), and instead serves as a good example of how a cumulative body of knowledge should develop in organizational science
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