The thermoelectric material ZnSb has been studied intensively in recent years and has shown promising features. The other zinc-antimonide compound, Zn 4 Sb 3 has remarkable low thermal conductivity, but it is accompanied with phase transitions at moderate temperature and has inherent stability problems. Compared to that, ZnSb is relatively phase stable and has a relative high charge carrier mobility and Seebeck coefficient, thus yielding a decent power factor. Meanwhile, its thermal conductivity can be reduced by means of nanostructuring, thus giving a good figure of merit at moderate temperatures, 400-600K. Many researchers have dedicated their efforts to study and improve ZnSb properties, and the figure of merit has been reported to be above one. Still, ZnSb as a thermoelectric material has features and behaviours that are not well-understood. The behaviour and properties of its intrinsic defects are not understood, but have interested researchers in recent years. This chapter intends to offer a comprehensive review on ZnSb to the readers. By combining own experiences from research on thermoelectric materials, the authors address the prospect for improving the thermoelectric properties of ZnSb and the concerns of transferring lab results to manufacturing.

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Rugate optical reflectance filters with position dependent reflectance peaks in the visible to near infrared spectrum were realized in porous silicon (PS). Filters with strong reflection peaks, near 100%, no detectable higher order harmonics and suppressed sidebands compared to discrete layer filters were obtained by varying the current density continuously and periodically during etching. An in-plane voltage up to 1.5 V was used to obtain refractive index and periodicity change along the filter surface resulting in reflectance peak shifts of up to 100 nm/mm in the direction of the voltage drop. The effect of the lateral change in optical parameters on the filter characteristics is studied by varying the gradient and comparing measurements at different positions with measurements on a non-graded filter. We have observed extra features in the reflectance spectrum of these graded filters compared with reflectance from a non-graded filter which is likely caused by the gradient.

We have performed new measurements of the temperature and doping dependency of the piezoresistive effect in p-type silicon. Piezoresistivity is one of the most common sensing principles of micro-electro-mechanical-systems (MEMS). Our measurements are performed in a specially designed setup based on the well-known 4 point bending technique. The samples are beams of full wafer thickness. To minimize leakage currents and to obtain uniform doping profiles, we have used SIMOX (Separation by IMplantation of OXygen) substrates with resistors defined in an epitaxial layer. Spreading resistance measurements show that the doping profiles are uniform with depth, while measurements of leakage current versus temperature indicate low leakage current. In this paper we present results for the doping concentration range from 1×1017 – 1×1020 cm−3 and the temperature range from –30 to 150 degrees Celsius. The results show a doping dependency of piezoresistivity well described by the current models. The measurements of the temperature dependency of the coefficients of piezoresistivity are compared to a linear model with a negative temperature coefficient whose absolute value decreases with increasing doping.

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