Optical properties of In/sub 0.8/Ga/sub 0.2/As self-assembled quantum dots on SiO/sub 2/-patterned [001] vicinal GaAs substrates
In this study, we investigated the optical properties of InGaAs SAQD on SiO/sub 2/-patterned exact and 5 /spl deg/-off [001] GaAs substrates. Also, we compared the discrete nature of the density of states in SAQDs for both starting materials.
Fabrication of wirelike InAs quantum dots on 2°-off GaAs (100) substrates by changing the thickness of the InAs layer
Wirelike InAs quatum dots (QDs) grown on 2°-off (100) GaAs substrates by changing the thickness of the InAs layer were successfully fabricated. The sizes of the InAs QDs along the step lines increased with increasing the thickness of the InAs layer, and their increases were attributed to transform of the InAs QDs into the wirelike InAs QDs. The optimal thicknesses of the InAs layers for the wirelike QDs and the interval of the wirelike QDs were significantly affected by the terrace width resulting from the bunching effect due to the thickness variations of the GaAs buffer layers grown on 2°-off (100) GaAs substrates. These results indicate that these wirelike InAs QDs are useful for applications in nanoelectronic devices, such as wrap gate single electron transistors.
Experience of using rating scales for the assessment of vocational trainees in general practice.
For two years trainers in the northern half of the south western region have been asked to assess their trainees with a condensed version of the new Manchester rating scales for vocational training in general practice and to send copies to the regional adviser. The condensed version retains the 23 scales but does not include the subscales. Trainers' workshops and comments from individuals suggested that no radical improvements to the scales were required and that they were an adequate statement of what was required from trainees. The response rate of 89% for returning at least one assessment and 38% for returning all three suggested that use of this condensed version would be more feasible than using the full version of the scales. Analysis of 86 first assessments and 48 sets of three assessments showed a range of variation both in trainee ratings and use of individual scales that was consistent with expectations. A lack of significant rank correlations between the scales indicated that each of the scales measured a different characteristic of behaviour. We suggest that the most useful way to achieve systematic assessment of vocational trainees is by the use of the 23 main rating scales, with regional variations where appropriate.