The effect of sulfur, iron, and chromium doping on the electrical characteristics of ZnSe single crystals was studied. The crystals, grown by the physical vapor transport method (PVT) at NASA Marshall Space Flight Center, were characterized by measuring electrical resistivity, capacitance, and dielectric constant using LCR meter. The morphology was studied by scanning electron microscopy to determine the crystallinity and micro defects. The measured resistivity and dielectric constant showed tunability as the function of frequency in the range of 100 Hz to 100,000 Hz, indicating the suitability of doped material for tuning devices. Besides, for the range from 50 mV to 1000mV, there was no difference in values for the studied frequency range, indicating no degradation or breakdown in the material. All doped ZnSe crystals with sulfur, iron, and chromium showed a similar trend as the function of frequency. Cr-ZnSe showed very high resistivity and lower dielectric constant compared to S-ZnSe and Fe-ZnSe crystals.

The performance of optical and electronic detectors and sensors are affected by surface and bulk impurities. In some cases, nanoscale thin films are used as detectors and their life cycle is significantly decreased. In the case of conformal shapes, surfaces with different polishing, decoration and geometries exhibit unusual wetting and nucleation characteristics for impurities and this requires continuous attention for cleaning. The situation for space borne components and vehicles surfaces exposed to wetting liquids requires remote cleaning. In the present paper, we report the effect of surface topographies of substrates with nanoengineered titanium oxide and copper oxide nanoparticles embodied in polystyrene and study the effect of the composites to create different hydrophobic characteristics with great potential for detectors and sensors operating in ultra-violet and infrared regions.

A great deal of research has been performed on refractive index n and extinction coefficient k due to varieties of applications in optical industries. The dispersion equation is described for the photons of varying energies and their interactions with materials since there is a strong correlation of n and k with wavelength. Measurements based on reflectance can be expensive and are very difficult due to compositional variations. We present a low-cost reflectance probe fiber optics designed in-house to determine the absorption coefficients and refractive index of solids. The solutions using a modified Beer-Lamberts Law and merging the concentration and extinction coefficient terms into an absorption coefficient, α, can be given by the equation I = I 0 exp (-α* d) where I is the transmitted intensity, I 0 is incident intensity and d is the thickness. We have experimented with several semiconductor compounds for this study.

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