Valley degeneracy in biaxially strained aluminum arsenide quantum wells

This paper details a complete formalism for calculating electron subband energy and degeneracy in strained multi-valley quantum wells grown along any orientation with explicit results for the AlAs quantum well case. A standardized rotation matrix is defined to transform from the conventional- cubic-cell basis to the quantum-well-transport basis whereby effective mass tensors, valley vectors, strain matrices, anisotropic strain ratios, and scattering vectors are all defined in their respective bases. The specific cases of (001)-, (110)-, and (111)-oriented aluminum arsenide (AlAs) quantum wells are examined, as is the unconventional (411) facet, which is of particular importance in AlAs literature. Calculations of electron confinement and strain in the (001), (110), and (411) facets determine the critical well width for crossover from double- to single-valley degeneracy in each system. The notation is generalized to include miscut angles, and can be adapted to other multi-valley systems. To help classify anisotropic inter-valley scattering events, a new primitive unit cell is defined in momentum space which allows one to distinguish purely in-plane inter-valley scattering events from those that requires an out-of-plane momentum scattering component.Comment: 17 pages, 4 figures, 2 table

Mechanical Dissipation in Silicon Flexures

The thermo-mechanical properties of silicon make it of significant interest as a possible material for mirror substrates and suspension elements for future long-baseline gravitational wave detectors. The mechanical dissipation in 92um thick single-crystal silicon cantilevers has been observed over the temperature range 85 K to 300 K, with dissipation approaching levels down to phi = 4.4E-7.Comment: 7 pages. Accepted by Phys Lett A, submitted for publication on 28 October 200

Walter S. Boernstein Collection. 1927-1974

The collection holds published and unpublished scholarly writings by the physician Walter S. Boernstein, primarily on perception, psychology, neurology and physiology. Also included are an obituary and a scholarly article by his sister, Kaethe Boernstein.Folder 1:Kaethe Boernstein: "Walter S. Boernstein M.D. : In memoriam", 5 page typescript; undated.Kaethe Boernstein: "Das Studium der Hormone in der Gewebezuechtung", 38 page, handwritten manuscript on hormones in tissue growth; [1927].Walter S. Boerstein: "Dear Sir Julian", 3 page, typed letter discussing scientific and philosophical issues; September 24, 1965.Offprints of scholarly articles by Walter Boernstein in German and international journals; 1928-1968.Folder 2:Typed drafts with handwritten corrections of scholarly articles by Walter S. Boernstein with dedications to his sister, Kaethe Boernstein; 1950s-1970s.Physician and researcher in neurology, psychology and physiology. Born in Berlin to a professor of chemistry, he studied in Freiburg, Heidelberg and Berlin before pursuing a career in neurological research related to sensory perception at Frankfurt, Bonn and Berlin. Expelled from his post in Berlin in 1933, he went into private practice before emigrating in 1935 to England and in 1937 to the US. Did research at London School of Economics, Oxford, Yale before settling at New York University in the 1940s.digitize

Leitfaden der Wetterkunde. Gemeinverständlich bearbeitet.

Bibliography, p. 209-222.Mode of access: Internet

Gottfried P&uquets ErKenntnistheorie und MetapnysiK.

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