Biomedical subjects

K P O'Donnell

Publications and source records attributed to K P O'Donnell.

At least 19 recordsLinked to original sources

PubMed2006

Anomalous ion channeling in AlInN/GaN bilayers: determination of the strain state.

Monte Carlo simulations of anomalous ion channeling in near-lattice-matched AlInN/GaN bilayers allow an accurate determination of the strain state of AlInN by Rutherford backscattering or channeling. Although these strain estimates agree well with x-ray diffraction (XRD) results, XRD composition estimates are shown to have limited accuracy, due to a possible deviation from Vegard's law, which we quantify for this alloy. As the InN fraction increases from 13% to 19%, the strain in AlInN films changes from tensile to compressive with lattice matching predicted to occur at [InN] = 17.1%.

Journal Article↗

PubMed2002

Characterization of nitride thin films by electron backscatter diffraction.

Thin films incorporating GaN, InGaN and AlGaN are presently arousing considerable excitement because of their suitability for UV and visible light-emitting diodes and laser diodes. However, because of the lattice mismatch between presently used substrates and epitaxial nitride thin films, the films are of variable quality In this paper we describe our preliminary studies of nitride thin films using electron backscattered diffraction (EBSD). We show that the EBSD technique may be used to reveal the relative orientation of an epitaxial thin film with respect to its substrate (a 90 degrees rotation between a GaN epitaxial thin film and its sapphire substrate is observed) and to determine its tilt (a GaN thin film was found to be tiltedby 13 +/- 1 degrees towards [1010]GaN), where the tilt is due to the inclination of the sapphire substrate (cut off-axis by 10 degrees from (0001)sapphire towards (1010)sapphire). We compare EBSD patterns obtained from As-doped GaN films grown by plasma-assisted molecular beam epitaxy (PA-MBE) with low and high As4 flux, respectively. Higher As4 flux results in sharper, better defined patterns, this observation is consistent with the improved surface morphology observed in AFM studies. Finally, we show that more detail can be discerned in EBSD patterns from GaN thin films when samples are cooled.

Journal Article↗

PubMed1996

Hospitals acquiring local businesses: the art and challenge of buying beyond the four walls.

As managed care pushes hospitals to redesign themselves into "integrated health care delivery systems," hospital executives are faced with "make or buy" decisions for a variety of alternate site care businesses. This article dissects the nuances of the buy option, which involves some rather subtle issues often new to most hospital-based executives.

Community Health Services↗

PubMed1994

Home health care: the pivotal link in the creation of a new health care delivery system.

Health care reform has challenged the home care industry to reemerge as the primary site for the delivery of health care, just as it was in the beginning of the 20th century. The factors driving the growth in this industry are discussed in this article, with an overview of what can be expected in a managed care environment. An analysis of the current marketplace and predictions for the expanded role of the home health care industry in the future are outlined.

Capitation Fee↗

PubMed1993