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  • 1
    Electronic Resource
    Electronic Resource
    X-ray reciprocal-space mapping of strain relaxation and tilting in linearly graded InAlAs buffers (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 3578-3584 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The extent of relaxation and orientation of linearly graded InxAl1-xAs (x=0.05–0.25) buffers grown on GaAs were examined using a novel x-ray diffraction reciprocal-space mapping technique (kmap). Samples were grown at temperatures ranging from 370 to 550 °C. The fractional relaxation of the buffers grown between 470 and 550 °C was essentially identical (77%) and symmetric in orthogonal 〈110〉 directions. These buffers are believed to be in equilibrium indicating that the incomplete relaxation is not a kinetic effect. The extent of relaxation was less than that expected for equilibrium relaxation in the absence of dislocation–dislocation interactions indicating that such interactions must be considered to accurately predict the extent of relaxation. The saturation of the relaxation as a function of temperature indicates that at the grading rate used (8% In/μm or 0.69% strain/μm), we are not working in a growth regime where the relaxation is nucleation limited. In addition, all the buffers are slightly tilted with respect to the GaAs substrate about [11¯0] toward the [110] direction suggesting either a bias in the dislocation types in the boule-grown GaAs, or a bias in the way in which α and β dislocations interact with unintentional substrate miscuts. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.361410
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  • 2
    Electronic Resource
    Electronic Resource
    Fabry–Perot reflectance modulator for 1.3 μm from (InAlGa)As materials grown at low temperature (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 62 (1993), S. 919-921 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the first all-semiconductor Fabry–Perot-cavity reflectance modulators operating at wavelengths of 1.32–1.33 μm. These devices were grown on a GaAs substrate using an intermediate, linearly graded InGaAs buffer layer terminating in an In0.33Ga0.67As layer. The Bragg reflector stacks of the Fabry–Perot structure are composed of InGaAs and InAlAs layers lattice matched to the buffer, and the active cavity region is an In0.4Ga0.6As/In0.26Al0.35Ga0.39As strained-layer superlattice. The key to obtaining device-quality material was low temperature growth (∼400 °C) of the entire structure. For a device with a 0.38-μm-thick active region and a 4 dB insertion loss, we obtained a contrast ratio of ∼3:1 at 4 V bias.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.108519
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  • 3
    Electronic Resource
    Electronic Resource
    Graded-composition buffer layers using digital AlGaAsSb alloys (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 2320-2322 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We describe step-graded digital-alloy buffers using alternate layers of Al0.5Ga0.5As and Al0.5Ga0.5As0.65Sb0.35 grown on GaAs substrates by molecular beam epitaxy. The buffers consist of three sets of superlattices with AlGaAs/AlGaAsSb layer thicknesses of 7.7/2.3 nm, 5.4/4.6 nm, and 3.1/6.9 nm, respectively, terminating in a lattice constant equal to that of bulk In0.32Ga0.68As. Transmission electron micrographs show that most of the misfit-generated dislocations lie near the steps in pseudoalloy composition, and atomic force micrographs indicate a rms surface roughness of 3.6 nm. A 20.5-period lattice-matched InGaAs/InAlAs reflector stack grown on such a buffer has a peak reflectivity of 98% near 1.3 μm. These buffers provide potentially useful substrates for optoelectronic device applications near 1.3 μm using strained InGaAs active regions. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.114331
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  • 4
    Electronic Resource
    Electronic Resource
    InGaAs/GaAs multiple strained-layer structure grown on a lattice-matched InGaAs substrate wafer (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 1957-1959 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Growth of In0.15Ga0.85As/GaAs multilayers are reported on lattice matched In0.04Ga0.96As buffer layers using two different starting substrates: (1) a bulk, lattice-matched, Czochralski-grown In0.04Ga0.96As wafer, and (2) a bulk (unmatched) GaAs wafer. The structures, grown by molecular-beam epitaxy, consist of a 200-nm-thick undoped buffer plus a 28-1/2 period modulation-doped multilayer having 10-nm-thick In0.15Ga0.85As quantum wells and 25-nm-thick GaAs barriers doped over their 10-nm central region. The 4 K Hall mobility of the multilayer grown on the InGaAs substrate is 57% larger than the structure grown on GaAs, despite a low dislocation density observed in transmission electron micrographs of the latter. These results suggest that bulk ternary substrates can provide enhanced performance for future electronic and optoelectronic devices. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.113289
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  • 5
    Electronic Resource
    Electronic Resource
    A cost-effectiveness approach to the Norwegian follow-up programme in colorectal cancer (1997)
    Springer
    Annals of oncology 8 (1997), S. 1081-1087 
    Details
    ISSN: 1569-8041
    Keywords: colorectal cancer ; cost-effectiveness ; follow-up
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: Today, continued periodic follow-up of patients treated for colorectal cancer (CRC) seems often to be routine because of tradition, rather than its demonstrated value. Recently, the Norwegian Gastrointestinal Cancer Group (NGICG) has recommended a standard surveillance programme in this malignancy. In this protocol patients are suggested followed for four years with CEA monitoring, ultrasound of the liver, chest radiograph and colonoscopy at regular intervals. Material and methods: In this study, the cost-effectiveness of this programme was addressed employing Norwegian cost data and data from the Cancer Registry of Norway. Clinical data from the existing English language literature was used in the analysis. Results: The basic cost of the NGICG recommended programme was £1,232 per patient. Including extended investigation due to suspected relapse in 45% of cases, the figure raised to £1,943 per patient. The cost per life year saved was indicated to £9,525–£16,192. The corresponding cost per quality adjusted life year (QALY) was indicated to £11,476–£19,508. Conclusion: We conclude the NGICG recommended follow-up programme in CRC cost-effective. Excluding CEA monitoring may improve the cost-effectiveness.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008265614183
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  • 6
    Electronic Resource
    Electronic Resource
    Adjuvant chemotherapy (5-fluorouracil and levamisole) in Dukes' B and C colorectal carcinoma. A cost-effectiveness analysis (1997)
    Springer
    Annals of oncology 8 (1997), S. 65-70 
    Details
    ISSN: 1569-8041
    Keywords: adjuvant therapy ; colorectal carcinoma ; cost-effectiveness analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: Adjuvant chemotherapy (5-fluorouracil, levamisole) is nowstandard practice in the treatment of Dukes' B and C coloretal carcinoma(CRC), and this has increased the financial burden on health care systemsworld-wide. Patients and methods: Between 1993 and 1996, 95 patients in northernNorway were included in a national randomised CRC study, and assigned tosurgery plus adjuvant chemotherapy or surgery alone. In April 1996, 94 of thepatients were evaluable and 82 were still alive. The total treatment costs(hospital stay, surgery, chemotherapy, administrative and travelling costs)were calculated. A questionnaire was mailed to all survivors for assessmentof the quality of their lives (QoL) (EuroQol questionnaire, a simpleQoL-scale, global QoL-measure of the EORTC QLQ-C30), and 62 of them(76%) responded. Results: Adjuvant chemotherapy in Dukes' B and C CRC raised the totaltreatment costs by £3,360. The median QoL was 0.83 (0–1 scale) in botharms. Employing a 5% discount rate and an improved survival of adjuvanttherapy ranging from 5% to 15%, we calculated the cost of onegained quality-adjusted life-year (QALY) to be between £4,800 and £16,800. Conclusion: Using a cut-off point level of £20,000 per QALY, adjuvantchemotherapy in CRC appears to be cost-effective only when the improvement in5-year survival is ≥5%. Adjuvant chemotherapy does not affectshort-term QoL.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008265905933
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  • 7
    Electronic Resource
    Electronic Resource
    Thermodynamic and transport properties of CeCu6 (1987)
    Springer
    Journal of low temperature physics 68 (1987), S. 371-397 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Measurements of the specific heat, magnetization, and transport properties (resistivity, thermoelectric power, and thermal conductivity) of single-crystal CeCu6 are reported with special emphasis on the effect of magnetic field. The relative field variations of the differential susceptibility, the coefficients of the linear temperature term of the specific heat, and theT 2 resistivity term are presented. They are directly related to the field curvature of the magnetization, indicating the itinerant nature of thef electrons. The Wilson ratio reaches a maximum atH=H*, which may correspond to a crossover from a low-field phase in which antiferromagnetic correlations dominate, to a highly polarized phase. Intersite coupling seems to play an important role in heavy-fermion compounds. Another interesting result is the occurrence of residual positive magnetoresistivity, which also appears to be a general feature of heavy-fermion compounds. The properties of CeCu6 are compared to those of otherf instability compounds and to present theories.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00682303
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