Photonic crystal (PhC) is a composite material, which demonstrated multiple light scattering phenomena due to different refractive indices. In preparation of PhC at least two periodic dielectric materials with different refractive indices are needed. This material can be used in various fields of optoelectronics. In this article, the characteristics of various PhC with their applications are reviewed. The photonic crystals can have different crystal structures but the most important characteristic is photonic strength. The band gap is very crucial to make optimum devices to control light.

Current nanostructure fabrication by etching is usually limited to planar structures as they are defined by a planar mask. The realization of three-dimensional (3D) nanostructures by etching requires technologies beyond planar masks. We present a method for fabricating a 3D mask that allows one to etch three-dimensional monolithic nanostructures using only CMOS-compatible processes. The mask is written in a hard-mask layer that is deposited on two adjacent inclined surfaces of a Si wafer. By projecting in a single step two different 2D patterns within one 3D mask on the two inclined surfaces, the mutual alignment between the patterns is ensured. Thereby after the mask pattern is defined, the etching of deep pores in two oblique directions yields a three-dimensional structure in Si. As a proof of concept we demonstrate 3D mask fabrication for three-dimensional diamond-like photonic band gap crystals in silicon. The fabricated crystals reveal a broad stop gap in optical reflectivity measurements. We propose how 3D nanostructures with five different Bravais lattices can be realized, namely cubic, tetragonal, orthorhombic, monoclinic and hexagonal, and demonstrate a mask for a 3D hexagonal crystal. We also demonstrate the mask for a diamond-structure crystal with a 3D array of cavities. In general, the 2D patterns on the different surfaces can be completely independently structured and still be in perfect mutual alignment. Indeed, we observe an alignment accuracy of better than 3.0 nm between the 2D mask patterns on the inclined surfaces, which permits one to etch well-defined monolithic 3D nanostructures.

Many efforts are devoted worldwide to control emission and propagation of light using nanophotonic metamaterials [1]. Of particular interest are 3D photonic band gap crystals in which light is forbidden to propagate in all directions and for all polarizations. Nevertheless it remains a great challenge to fabricate such 3D nanophotonic materials. The widely employed fabrication of 3D photonic crystals with deposition techniques suffers from nanocrystallinity or even amorphous backbones with concomitant impurities, which causes undesired scattering and absorption[2]. A powerful alternative is to use a high purity single crystalline silicon for the fabrication of nanophotonic materials. The use of high-purity silicon and reactive ion etching allowed to demonstrate for the first time a strong inhibition of spontaneous emission inside a 3D photonic band gap crystal [3]. Nevertheless the fabrication procedure requireds an involved alignment of masks on two inclined planes with respect to each other significantly slows progress in this area [4].

In this paper we present a method to deposit thin films of bismuth with sub-nanometer surface roughness for application to diamagnetic levitation. Evaporated films of bismuth have a high surface roughness with peak to peak values in excess of 100 nm and average values on the order of 20 nm. We expose the smooth backside of the films using a template stripping method, resulting in a great reduction of the average surface roughness, to 0.8 nm. Atomic force microscope and X-ray diffraction measurements show that the films have a polycrystalline texture with preferential c-axis orientation. On the back side of the film, fine grains are grouped into larger clusters. Cantilever resonance shift measurements indicate that the Young's modulus of the films is on the order of 20 GPa.

Three dimensional photonic band gap crystals with a cubic diamond‐like symmetry are fabricated. These so‐called inverse‐woodpile nanostructures consist of two perpendicular sets of pores in single‐crystal silicon wafers and are made by means of complementary metal oxide–semiconductor (CMOS)‐compatible methods. Both sets of pores have high aspect ratios and are made by deep reactive‐ion etching. The mask for the first set of pores is defined in chromium by means of deep UV scan‐and‐step technology. The mask for the second set of pores is patterned using an ion beam and carefully placed at an angle of 90° with an alignment precision of better than 30 nm. Crystals are made with pore radii between 135–186 nm with lattice parameters a = 686 and c = 488 nm such that a/c = √2; hence the structure is cubic. The crystals are characterized using scanning electron microscopy and X‐ray diffraction. By milling away slices of crystal, the pores are analyzed in detail in both directions regarding depth, radius, tapering, shape, and alignment. Using optical reflectivity it is demonstrated that the crystals have broad reflectivity peaks in the near‐infrared frequency range, which includes the telecommunication range. The strong reflectivity confirms the high quality of the photonic crystals. Furthermore the width of the reflectivity peaks agrees well with gaps in calculated photonic band structures.

Photonic crystals control light propagation at a fundamental level. Photonic crystals are ordered composite materials with a spatially varying dielectric constant that has a periodicity of the order of the wavelength of light. Frequency gaps emerge for which light cannot propagate inside such structure due to Bragg diffraction. These frequency gaps appear in experiments as stopbands. This paper investigates stopbands in directions of high symmetry for two-dimensional photonic crystals. Surprisingly, a stopband below the first order Bragg condition was observed. This result is valid not only for photonic crystals, but for wave propagation in periodic media in general. This has implications for crystallography, scattering of phonons and band gap formation.

We study optical properties of CMOS-compatible 3D silicon inverse woodpile photonic crystals in the near-infrared. Spectrally overlapping reflectivity peaks for both polarizations and many directions form the experimental signature of a photonic band gap with a relative bandwidth up to 16%.

We present for the first time the combined measured piezoelectric and mechanical properties of epitaxial, (110) oriented $Pb(Zr_xTi_{1-x})$ (PZT) thin films grown on microfabricated silicon cantilevers using pulsed laser deposition (PLD, x=0.4, 0.52, 0.6 and 0.8). The grown PZT thin films develop a strong (110) preferred orientation, which results in an effective piezoelectric coefficient (d33,f) of 123 pm/V at the morphotropic phase boundary (Zr/Ti = 52/48). This value is 70% higher compared to sol-gel deposited films with an equal Young’s modulus [1]. The Young’s modulus of the PZT thin films was determined by measuring the shift in resonancefrequency of microfabricated cantilevers (shown in Fig. 1) both before and after deposition of the films by means of a scanning laser-Doppler vibrometer. To this end, we developed a model to calculate the Young’s modulus from the resonance frequency shift which includes an essential correction for the undesired undercut that is unavoidably introduced during the release of cantilevers [2]. The obtained Young’s modulus is independent on cantilever length, as expected. For a 100 nm thick PZT film with a Zr/Ti ratio of 60/40, the mean value of the measured Young’s modulus was found to be 122 GPa with a standard error of ± 1.3 GPa. Fig.2 shows an increase of the Young’s modulus of the PZT thin films with increasing Zr/(Zr+Ti) ratio. The PLD-PZT thin film presented in this work combines excellent piezoelectric properties with a high Young’s modulus, and is therefore a promising and exciting candidate for the active device layer in actuators and highly sensitive MEMS sensors.

The Young’s modulus of thin films can be determined by deposition on a micronsized Si cantilever and measuring the resonance frequency before and after deposition. The accuracy of the method depends strongly on the initial determination of the mechanical properties and dimensions of the cantilever. We discuss the orientation of the cantilever with respect to the Si crystal, and the inevitable undercut of the cantilever caused by process inaccuracies. By finite element modelling we show that the Young’s modulus should be used instead of the analytical plate modulus approximation for the effective Young’s modulus of Si cantilevers used in this work for both the 〈100〉 and 〈110〉 crystal orientation. Cantilever undercut can be corrected by variation of the cantilever length. As an example, the Young’s modulus of PbZr0.52Ti0.48O3 (PZT) thin films deposited by pulsed laser deposition (PLD) was determined to be 99GPa, with 1.4GPa standard error.

Accurate manipulation of small objects is becoming more and more important. Besides accurate manipulation, the demand for small manipulators is also increasing. Some examples are high-density data storage, (digital) light processing, accelerometers, rate sensors, and the use of cantilevers in atomic force microscopy. Another example where small and accurate manipulators are beneficial is inside an electron microscope, for sample as well as beam manipulation. This work presents the design, fabrication and experimental validation of a thermal displacement sensor for accurate measurement of the position of a MEMS stage. The sensor was integrated with the manipulation stage in a singlemask production process.

In this contribution we present the compositional dependence of the longitudinal piezoelectric coefficient (d33,f), residual stress and Young's modulus of Pb(Zrx,Ti1-x)O3 (PZT) thin films. Pulsed laser deposition (PLD) was used to deposit epitaxial PZT thin films with a preferred orientation on silicon cantilevers. By using PLD, excellent piezoelectric properties of the PZT were observed which makes it an exciting piezoelectric material for the development of actuators and highly sensitive sensors. Our investigation of the compositional distribution of the piezoelectric coefficient (d33,f) for 250 nm thick films shows a maximum value of 93 pm/V for x=0.52. The static deflection of the cantilevers, measured after the deposition of PZT thin films was used to determine the residual stress for various compositions. The observed trend in the residual stress of PZT thin films is attributed to the varying coefficient of thermal expansion for different compositions. The Young's modulus of the PZT thin films was determined by measuring the flexural resonance frequency of the cantilevers both before and after the deposition. The Young's modulus increases for the zirconium rich PZT compositions, which is in agreement with the trend observed in their bulk ceramic counterparts.

The feasibility of 3D self-assembly of milli-magnetic particles that interact via magnetic dipolar forces is investigated. Typically magnetic particles, such as isotropic spheres, self-organize in stable 2D configurations. By modifying the shape of the particles, 3D self-assembly may be enabled. The design of the particles and the experimental setup are presented. The magnetic configurations of simple particle arrangements are obtained via energy minimization in simulations. The simulations show that a 3D configuration can become energetically favourable over 2D configurations, if the shape of the particle is modified.