B.K. Reddy

Optical and electrical studies of vapour phase grown Cd1-xCoxTe crystals.

The optical properties of vapour phase grown crystals of diluted magnetic semiconductor (DMS) Cd1-xCoxTe were investigated for x=0.001, 0.003, 0.005, 0.007 and 0.009. The reflectivity spectra exhibited a regular shift in the fundamental absorption edge (E0) with composition x. The reflectivity spectra for the present samples of Cd1-xCoxTe of all compositions exhibit broad bands at 5300 and 11,100cm(-1) due to the transitions of 4A2-->4T1 (F) and 4A2-->4T1 (P), respectively. Temperature dependence of resistivity revealed semiconducting behaviour of the samples. Hot probe test revealed that all the samples exhibited p-type conductivity.

DESIGN OPTIMIZATION, FABRICATION AND TESTING OF A CAPACITIVE SILICON ACCELEROMETER USING AN SOI APPROACH

In this paper the design, fabrication and testing of the capacitive micro accelerometer with Silicon On Insulator (SOI) approach is presented. The beam location with respect to a rectangular mass is optimized, using finite element analysis (FEM) to minimize cross axis sensitivity. It is demonstrated that a simple KOH etching with the addition of the tert-butanol can be easily adopted to fabricate the accelerometer structure without any convex undercutting effects. The devices are tested by electrostatic actuation.

Electrical Properties of Thermal Evaporated Cd1-xMnxS Nanocrystalline Films

Thin films of Cd 1-x Mn x S (0 £ x ≤ 0.5) were deposited on glass substrates by thermal evaporation. All the films were deposited at 300 K and annealed at 373, 473, and 573 K for 1 h in a high vacuum in the range 10 -4 Pa. The as-deposited and the annealed films were characterized for composition, structure, and microstructure by using energy-dispersive X-ray, X-ray diffraction, scanning electron microscopy, and atomic force microscopy (AFM). The electrical properties were studied by Hall effect measurement. Electrical conductivity was studied in the temperature range 190-450 K. AFM studies showed that all the films were in nanocrystalline form with grain size varying in the range between 36 and 82 nm. Grain size studies showed a definite increase with annealing temperature. All the films exhibited wurtzite structure of the host material. The lattice parameter varied linearly with composition, following Vegards law in the entire composition range. Grain size, electrical conductivity, Hall mobility, carrier concentration, and activation energy varied, exhibiting either maxima or minima at x = 0.3.

Structural and Electrical Properties of Resistive Thermal Evaporated Cd1‐xMnxS Nano‐Crystalline Films

Thin films of Cd1‐xMnxS (0≤×≤0.5) were prepared on window glass substrates by resistive vacuum thermal evaporation. All the films were deposited at 300 K and the films annealed at 373 K, 473 K and 573 K for 1 hour in a vacuum of 10−6 m · bar. The as‐deposited and the annealed films were characterized by EDAX, XRD, AFM, electrical conductivity and Hall Effect studies.