X-ray Diffraction Mapping Of Strain Fields And Chemical Composition Of Sige:si(001) Quantum Dot Molecules

A variety of surface morphologies can be formed by controlling kinetic parameters during heteroepitaxial film growth. The system reported is a Si0.7 Ge0.3 film grown by molecular beam epitaxy at 550°C and a 1 s deposition rate, producing quantum dot molecule (QDM) structures. These nanostructures are very uniform in size and shape, allowing strain mapping and chemical composition evaluation by means of anomalous x-ray diffraction in a grazing incidence geometry. Tensile and compressed regions coexist inside QDMs, in accordance with the finite-element calculations of lattice relaxation. The Ge content was found to vary significantly within the structures, and to be quite different from the nominal composition. © 2006 The American Physical Society.7312Chen, K.M., (1995) Appl. Phys. Lett., 66, p. 34. , APPLAB 0003-6951 10.1063/1.114172Goldfarb, I., (1997) Phys. Rev. Lett., 78, p. 3959. , PRLTAO 0031-9007 10.1103/PhysRevLett.78.3959Mo, Y.-W., (1990) Phys. Rev. Lett., 65, p. 1020. , PRLTAO 0031-9007 10.1103/PhysRevLett.65.1020Tomitori, M., (1994) Appl. Surf. Sci., 76-77, p. 322. , ASUSEE 0169-4332Floro, J.A., (1998) Phys. Rev. Lett., 80, p. 4717. , PRLTAO 0031-9007 10.1103/PhysRevLett.80.4717Ross, F.M., (1998) Phys. Rev. Lett., 80, p. 984. , PRLTAO 0031-9007 10.1103/PhysRevLett.80.984Medeiros-Ribeiro, G., (1998) Science, 279, p. 353. , SCIEAS 0036-8075 10.1126/science.279.5349.353Chaparro, S.A., (1999) Phys. Rev. Lett., 83, p. 1199. , PRLTAO 0031-9007 10.1103/PhysRevLett.83.1199Denker, U., (2005) Appl. Phys. Lett., 772, p. 599. , APPLAB 0003-6951Gray, J.L., (2002) Appl. Phys. Lett., 81, p. 2445. , APPLAB 0003-6951 10.1063/1.1509094Vandervelde, J.T.E., (2003) Appl. Phys. Lett., 83, p. 2505. , APPLAB 0003-6951Jesson, D.E., (1996) Phys. Rev. Lett., 77, p. 1330. , PRLTAO 0031-9007 10.1103/PhysRevLett.77.1330Gray, J.L., (2004) Phys. Rev. Lett., 92, p. 135504. , PRLTAO 0031-9007 10.1103/PhysRevLett.92.135504Schülli, T.U., (2003) Phys. Rev. Lett., 90, p. 066105. , PRLTAO. 0031-9007. 10.1103/PhysRevLett.90.066105Malachias, A., (2003) Phys. Rev. Lett., 91, p. 176101. , PRLTAO 0031-9007 10.1103/PhysRevLett.91.176101Magalhães-Paniago, R., (2002) Phys. Rev. B, 66, p. 245312. , PRBMDO. 0163-1829. 10.1103/PhysRevB.66.245312Krause, B., (2005) Phys. Rev. B, 72, p. 085339. , PRBMDO 0163-1829 10.1103/PhysRevB.72.085339Zhang, Y., (2001) J. Appl. Phys., 90, p. 4748. , JAPIAU 0021-8979 10.1063/1.1407311Gray, J.L., (2005) Phys. Rev. B, 72, p. 155323. , PRBMDO 0163-1829 10.1103/PhysRevB.72.155323Tersoff, J., (1998) Phys. Rev. Lett., 81, p. 3183. , PRLTAO 0031-9007 10.1103/PhysRevLett.81.318

Researching the gender division of unpaid domestic work: practices, relationships, negotiations, and meanings

The paper focuses on the potential of quantitative research methods for sociologists who research the gender division of unpaid domestic work. To begin, it reflects on the emergence of the sociological interest in unpaid domestic work and identifies an early core concern with making invisible work visible. It is argued that quantitative research methods provide us with the most valuable opportunities for ‘recognising’ unpaid domestic work since they facilitate larger scale representative projects. However the data in most of the large scale surveys are scant, and fail to reflect developments in the conceptualisation of unpaid domestic work. Four areas of concern to contemporary sociology are identified: domestic work practices, relationships, negotiations and meanings. Given the complex questions that these four sub- topics raise, the paper proposes a range of sub-areas as a focus for ongoing sociological research into unpaid domestic work. It is concluded that despite the methodological challenges presented, detailed indicators of the multiple dimensions of unpaid domestic work need to be agreed so that valid information can be collected as routinely in large scale surveys as are those on paid work

Internet use and time use: the importance of multitasking

Scholars are beginning to question the impacts of the Internet for the conceptualisation of time and time use. However, discussion in terms of the impacts of the Internet for multitasking has been absent from this debate. Multitasking has, until recently, been a 'forgotten dimension' of time use research. The phenomenon has long been recognised as important, yet it is only in the past decade that time use researchers have begun seriously both to record and analyse related data. Such studies have shown that a more fully informed understanding of the true extent of time use and activity participation can emerge through the consideration of multitasking. This, in turn, can present a more accurate picture upon which measures of change in time use can be assessed. This paper is concerned with an exploratory discussion of the impact of the inclusion of multitasking data upon perception of change in time use as a result of Internet use. Following theoretical discussion, the paper presents evidence from a longitudinal, diary-based panel study with c. 100 participants and a questionnaire survey with 1,000 participants. The paper explores the prevalence of multitasking and reveals clear implications of Internet use for the same, concluding that those seeking to understand the influence of Internet use upon time use must include multitasking in their analysis, if they are to avoid an incomplete and potentially misleading account of time use (and change therein) in the information age