The quantitative characterization of SiGe layers by analysing rocking profiles in CBED patterns.

Convergent beam electron diffraction is used for the quantitative determination of layer thickness, composition and strain in pseudomorphic Si/SiGe two- and three-layer systems grown by molecular beam epitaxy. By using plan-view specimens, we are able to avoid the influence of surface relaxation which generally complicates the determination of strains in cross-sectional specimens. For quantitative strain determination, rocking curves of Bragg lines in energy-filtered convergent beam electron diffraction patterns are analysed. The experimentally obtained rocking curves are compared with kinematical calculations by a computerized fit procedure. The resulting layer parameters are then further refined by a dynamical simulation. Results for the strains obtained with this technique are in good agreement with theoretical values. With this method layer thickness is measured down to monolayer precision. The accuracy of the strain analysis depends on the sequence and thickness of the layers.

Board members with a mission. A system board makes community needs its business.

The system board of the Sisters of Charity of the Incarnate Word Health Care System (SCH), Houston, has been a leader in moving the system from a competitive model to one that is mission driven. By clearly articulating the mission, vision, and beliefs that are central to SCH, the board established a values-based framework for linking future challenges to tradition, thereby encouraging continuation of the original spirit and call of the founding sisters. In 1987 the SCH board initiated the concept of systemwide community mission projects by directing healthcare facilities to develop projects that address the needs of local vulnerable populations. And in 1991 the SCH board called for the establishment of charity programs and services that directly respond to local community needs. It ordered a systemwide, multiphased community needs assessment at the local level. The mission projects that resulted focus on primary prevention, education and counseling, and information and referral services. The board has taken other actions that demonstrate its community-centered perspective in ensuring the system's commitment to mission. For example, when an inner-city hospital in Houston closed, the board appointed a task force to determine what the community identified as its most urgent unmet need. The result is a program to address the needs of vulnerable older adults. And in 1992 the SCH board approved the appointment of a capital process review team. It now takes a more global social accountability view when allocating funding.