IBM

About: IBM is a company organization based out in Armonk, New York, United States. It is known for research contribution in the topics: Layer (electronics) & Cache. The organization has 134567 authors who have published 253905 publications receiving 7458795 citations. The organization is also known as: International Business Machines Corporation & Big Blue.

Effective electron mobility in Si inversion layers in metal–oxide–semiconductor systems with a high-κ insulator: The role of remote phonon scattering

Abstract: The high dielectric constant of insulators currently investigated as alternatives to SiO2 in metal–oxide–semiconductor structures is due to their large ionic polarizability. This is usually accompanied by the presence of soft optical phonons. We show that the long-range dipole field associated with the interface excitations resulting from these modes and from their coupling with surface plasmons, while small in the case of SiO2, for most high-κ materials causes a reduction of the effective electron mobility in the inversion layer of the Si substrate. We study the dispersion of the interfacial coupled phonon-plasmon modes, their electron-scattering strength, and their effect on the electron mobility for Si-gate structures employing films of SiO2, Al2O3, AlN, ZrO2, HfO2, and ZrSiO4 for “SiO2-equivalent” thicknesses ranging from 5 to 0.5 nm.

Growth dynamics of pentacene thin films

Abstract: The recent demonstration of single-crystal organic optoelectronic devices has received widespread attention1,2,3,4. But practical applications of such devices require the use of inexpensive organic films deposited on a wide variety of substrates. Unfortunately, the physical properties of these organic thin films do not compare favourably to those of single-crystal materials. Moreover, the basic physical principles governing organic thin-film growth and crystallization are not well understood. Here we report an in situ study of the evolution of pentacene thin films, utilizing the real-time imaging capabilities of photoelectron emission microscopy. By a combination of careful substrate preparation and surface energy control, we succeed in growing thin films with single-crystal grain sizes approaching 0.1 millimetre (a factor of 20–100 larger than previously achieved), which are large enough to fully contain a complete device. We find that organic thin-film growth closely mimics epitaxial growth of inorganic materials, and we expect that strategies and concepts developed for these inorganic systems will provide guidance for the further development and optimization of molecular thin-film devices.

Building text classifiers using positive and unlabeled examples

Abstract: We study the problem of building text classifiers using positive and unlabeled examples. The key feature of this problem is that there is no negative example for learning. Recently, a few techniques for solving this problem were proposed in the literature. These techniques are based on the same idea, which builds a classifier in two steps. Each existing technique uses a different method for each step. We first introduce some new methods for the two steps, and perform a comprehensive evaluation of all possible combinations of methods of the two steps. We then propose a more principled approach to solving the problem based on a biased formulation of SVM, and show experimentally that it is more accurate than the existing techniques.

Convex hulls of finite sets of points in two and three dimensions

Abstract: The convex hulls of sets of n points in two and three dimensions can be determined with O(n log n) operations. The presented algorithms use the “divide and conquer” technique and recursively apply a merge procedure for two nonintersecting convex hulls. Since any convex hull algorithm requires at least O(n log n) operations, the time complexity of the proposed algorithms is optimal within a multiplicative constant.