Semiconducting CdTe microcrystalline was successfully doped in SiO2 films by the magnetron rf-sputtering technique. The average size of the microcrystalline depended on the relative area and location of the CdTe chips on the target, as well as the postannealing time; and that of as-deposited films varied from 22 A to 62 A. From the optical absorption spectra, the absorption edge of the films clearly exhibited blue shifts compared to the bulk CdTe. Thus the quantum size effect could be found for these films.

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CdTe films can be grown epitaxially on InSb(100) by chemical sputtering in H2. The crystalline quality of the epitaxial layers is improved when the substrate temperatures are in the range of 200 to 250°C at a high rf discharge power of 400 W. In channeling experiments employing Rutherford backscattering spectrometry, the χmin (aligned yield/random yield) in the film prepared at 270°C and 400 W is 9.5%. A lattice strain of 0.05% is obtained from the results of X-ray diffraction. These values show that the crystalline quality of the epitaxial film grown by H2 sputtering is superior to the film grown by Ar sputtering.

GaSb(Bi)/Al0.2Ga0.8Sb single quantum wells are characterized by a Fourier transform infrared spectrometerbased photoreflectance method at 77 K. Spatially direct and indirect transitions between the electronic levels at and above the effective band gap are well resolved. The shifts of the electronic levels with Bi incorporation are identified quantitatively. The results show that the upshift of the valence band edge is clarified to be dominant, while the Bi-induced downshift of the conduction band edge does exist and contributes to the band gap reduction in the GaSbBi quantum-well layer by (29±6)%.

A n example is analysed, in which at every point of a circuit an electrostatic and a nonelectrostatic field coexist, in order to clarify the concepts of EMF and potential difference.Aclolowleagmenb I am pleased to acknowledge helpful conversations with J L Arias, and the comments of the referees. ReferencesMorton N 1980 Eur. J. Phys. 1 138 Panofsky W K H and Phillips M 1971 Classical Electricity and Magnetism 2nd edn (Massachussetts: Addison-Wesley) pp 119-20 tromagnetic Theory 2nd edn (Massachussetts: Addison-Wesley) pp 133-5 Varney R N and Fisher L H 1980 Am. J. Phys. 48 405 Reitz J R and Milford F J 1970 Foundations of Elec-