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Aluminum nitride (AlN) thin films with thicknesses from 20 to 100 nm were deposited on silicon, amorphous silica, silicon nitride, and vitreous carbon by plasma enhanced atomic layer deposition (PE-ALD). Trimethylaluminum (TMA) and a H2/N2 plasma mixture were used as precursors. We investigated the influence of deposition temperature and plasma parameters on the growth characteristics and the film properties of AlN. Stable PE-ALD growth conditions were obtained from 150 °C to the highest tested temperature of 300 °C. The growth rate, refractive index, and thickness homogeneity on 4″ wafers were determined by spectroscopic ellipsometry. X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and Rutherford backscattering spectrometry (RBS) were carried out to analyze crystallinity and composition of the films. Furthermore, the thermal conductivity and the film stress were determined. The stress was sufficiently low to fabricate mechanically stable free-standing AlN membranes with lateral dimensions of up to 2.2 × 2.2 mm2. The membranes were patterned with focused ion beam etching. Thus, these AlN membranes qualify as dielectric support material for a variety of potential applications.

An optical metamaterial, operating in between the MID/IR and the visible domain, which uses the effect of extreme coupling between closely spaced nanostructured gold metal plates and a planar gold substrate was realized by means of electron beam lithography and lift-off technique. This regime is only accessible by using an ultrathin oxide layer between metal plates and substrate, where the oxide layerisrealized by atomic layer deposition here. The involved fabrication is discussed in detail. The metamaterial shows the predicted effect of perfect absorption with multiple resonances in the spectral range from 100 THz to 600 THz. The plasmonic based resonance frequencies are very sensitive to the plate size of the grating and the spacer thickness.

Graphical abstractDisplay Omitted Highlights? Homogenous and sensitive SERS-substrates based on surface metalized resist gratings. ? The approach combines e-beam lithography, atomic layer deposition and silver evaporation. ? The SERS enhancement is 4-5 orders of magnitude compared with the un-patterned film. ? The method enables disposable SERS substrates by using imprint techniques. A method using microfabricated resist masks as highly homogenous and sensitive substrates for surface enhanced Raman spectroscopy (SERS) is introduced. Our approach combines e-beam lithography for a polymer (PMMA) mask preparation, atomic layer deposition of aluminum-oxide as protection layer for the PMMA mask and silver evaporation for the SERS-active metal film. Compared to our former investigations on silver deposited etched quartz SERS-substrates these polymer based SERS substrates are easier to fabricate while showing the same reproducible signal enhancement across the whole grating area. The presented method provides high potential as it uses low-cost imprint techniques to pave the way towards low-cost SERS substrates in the future.

Thermopile detectors are particularly well suited for spectral imaging, space science applications, track recording, presence detection and applications with low energy consumption. The purpose of this work is the fabrication of a surface-micromachined 2-D high detectivity thermopile array using a highly effective BiSb/Sb thermocouple materials combination. The thermoelectric array is built on 8x8 pixels with an active area of [email protected] in square, which are wired directly. Thermopile structure and absorber area are manufactured upon a sacrificial layer based on polyimide, which is removed at the end of the manufacturing process. Thermoelectric layers as well as wiring layers has been patterned almost exclusively by lift-off technique in order to obtain very small structure dimension with high reliability as well as high integration level. The active area of detectors can be equipped with two absorber types for different application, a broadband colloidal silver black layer as well as a quarter wavelength arrangement for the MIR wavelength range from 8 to [email protected] The detectivity of so manufactured FPAs is about 1x10^9 Jones exceeding most of the state-of-the-art thermopile detectors.

Cryogenic bolometers are adequate sensing devices for sub-millimeter observations. They are used for instrumentation in radio telescopes like the Atacama Pathfinder Experiment (APEX), which is a 12-m radio telescope in Chile's Atacama desert. Through its thin and dry atmosphere, star formation in the red-shifted early universe can be observed. A suitable bolometer has a high sensitivity and consists of several tens to hundreds of pixels that are combined to an array. To meet these requirements, we use transition edge sensors. They detect radiation by measuring a temperature increase in an appropriate absorber. For highest sensitivity, the absorber is only in weak thermal contact to its surroundings. This is achieved by placing it on a SiN membrane that is structured to further decrease the thermal coupling. A superconductor that is biased at its transition temperature serves as thermometer for the transition edge sensor. We present the fabrication of such devices and discuss encountered difficulties. Further, we briefly describe the incorporation of a sensor chip with an array of 39 pixels into an instrument that currently operates at APEX. For the fall of 2010 the installation of a 300 pixel array is scheduled.