Interferometric analysis of nanostructured surface profiles: correcting material-dependent phase shifts

We present a technique to correct interferometry for the material-dependent phase shift that accompanies reflection. Such corrections are needed for nanometer accuracy of surfaces that are not of homogeneous composition. We adapt the general theory of reflection from surfaces in which there are irregular and unresolved areas of several materials to treat the specific case in which only two materials are present, as is the case for many practical applications. We show, for the approximation of a large numerical aperture that collects all reflected light, how measurements of three quantities, together with known values of the optical constants, allow determination of the material-dependent phase shift at each position on the surface. We demonstrate with numerical simulation, appropriate to measuring a surface of alumina in which optically unresolved titanium carbide granules are embedded, that our approach also succeeds, with nanometer accuracy, when the numerical aperture is small. The method is discussed for use with a miniature interferometric phase sensor, but it has application to any interferometer.     

Modern internal-irradiation dosimetry

A graphical user interface making it possible to create initial data files automatically for calculating the radiation spectrum of a human body using the MCNP program and to perform graphical analyis of the computational results is described. The results of using the program developed to perform spectrometry of human-body radiation and internal dosimetry are desrcribed. The development of precise measurement methods, such as the spectrometry of human-body radiation, and the appearance of new methods for analyzing the results of measurements will make the monitoring of internal irradiation of workers in the nuclear power industry more accurate.Translated from Atomnaya Ènergiya, Vol. 97, No. 4, pp. 286–293, October, 2004.     

Electrical properties of thin PbTe films on Si substrates

An attempt was made to reduce the carrier concentration in thin PbTe films on Si substrates by optimizing deposition conditions. A modified hot-wall method was used for reproducible growth ofp-type films with 5 × 10¹⁵ < p(77 K) < 5 × 10¹⁷ cm^-3 andn-type films with 3 × 10¹⁵ < n(77 K) < 5 × 10¹⁶ cm^-3. The IR irradiation was found to have a significant effect on the temperature variation of film resistance. The activation energy of the IR-sensitivity centers was determined to be 0.11 ± 0.005 eV at room temperature and 0.18 ± 0.005 eV between 150 and 180 K.