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Supermemories are coming that will store an entire library or home-cinema collection on a single chip

Diffractive phase elements (DPE), consisting of a patterned UV-transparent layer on a UV-transparent substrate, were fabricated by three steps. A UV-absorbing SiO x -coating (x < 2) with a thickness matching to the required phase delay was deposited on a fused silica substrate. The coating was removed on a pixel array corresponding to a calculated two-dimensional quantized phase function (DPE-design). By a thermal annealing process the SiO x -coating was oxidised to UV-transparent SiO 2 , resulting in a UV-grade surface relief element.

Growing requirements for the optical and environmental stability, as well as the radiation resistance against high-power laser radiation, especially for optical interference coatings used in the ultraviolet spectral range, have to be met by new, optimised, thin-film deposition technologies. For applications in the UV spectral range, the number of useful oxide thin film materials is very limited due to the higher absorption at wavelengths near to the electronic bandgap of the materials. Applying ion-assisted processes offers the ability to grow dense and stable films, but in each case careful optimisation of the deposition process (evaporation rate, substrate temperature, bombarding gas, ion energy and ion current density) has to achieve a balance between densification of the layers and the absorption. High-quality coatings and multilayer interference systems with SiO/sub 2/ as the low- index material can be deposited by various physical vapour deposition technologies, including reactive e-beam evaporation, ion-assisted deposition and plasma ion-assisted deposition. In order to improve the degradation stability of dielectric mirrors for use in UV free-electron laser optical cavities, a comparative study of the properties of SiO/sub 2/, Al/sub 2/O/sub 3/ and HfO/sub 2/ single layers was performed, and was addressed to grow very dense films with minimum absorption in the spectral range from 200 to 300 nm. The films were deposited by low-loss reactive electron-beam evaporation, by ion-assisted deposition using a 'Mark II' ion source, and by plasma ion-assisted deposition using the advanced plasma source. Optical and structural properties of the samples were studied by spectral photometry, infrared spectroscopy, X-ray diffraction and reflectometry, as well as by investigation of the surface morphology. The interaction of UV radiation with photon energy values close to the bandgap was studied. For HfO/sub 2/ single layers, laser-induced damage thresholds at 248 nm were determined in the 1-on-1 and 1000-on-1 test modes as a function of the deposition technology and film thickness.

The demand to enhance the optical resolution, to structure and observe ever smaller details, has pushed the search for technological innovations and improvements. Induced mainly by the production of more powerful electronic circuits with the aid of projection lithography, optics developments in recent years can be characterized by the use of electromagnetic radiation with smaller wavelength. This paper covers some theoretical considerations, material aspects, design and different techniques of controlled fabrication of multilayer coated optics. Their potential applications for microlithography as well as alternative application fields like microscopy, spectroscopy, soft X-ray lasers and free electron lasers are also discussed.

Microelectronics made from silicon will soon be as small as they can physically be. The era of nanoelectronics dawns – where carbon could be king

We report on electron transport in growth direction and relaxation mechanisms in δ-doped GaAs-superlattices. In order to investigate pure electron transport, n-type δ–n–i–p–i structures sandwiched between two n+-cladding layers have been investigated, with doping induced barrier heights ΔV smaller than the band gap energy Eg of the host material. An exponential increase of the current is expected with increasing bias due to tunneling through a decreasing barrier. At elevated temperatures, thermally activation over the barriers becomes possible. A simple WKB-model describes the experimental data reasonably well. Moreover, a current step appears in the I–V characteristics at a critical field which is clearly below the breakthrough value. Opto-electrical measurements confirm the existence of holes in the structure at fields larger than the critical field. A model is presented which explains the photocurrent and electroluminescence measurements consistently. The key mechanism is based on a few ballistically traveling electrons that can gain enough energy for interband avalanche multiplication.

Slimline, efficient photovoltaics about to flop off the production line could revolutionise the business of generating electricity from sunlight