Quantum dots and quantum wires based on CdZnSe/ZnSe single quantum well heterostructures have been achieved using electron beam lithography and wet chemical etching. Photoluminescence spectra of the dot and wire structures show a blue shift due to lateral quantization for lateral dimensions below 40 nm. For the dot ground state, a lateral confinement energy of 16 meV is obtained for 28 nm diameter structures. For wires with widths on the order of 20 nm, lateral confinement energies of about 5 meV are observed. The dot diameter and wire width dependence of the emission energies can be described based on a square well potential and the measured sizes of the structures.

By electron beam lithography and a subsequent wet/dry etch process, optically active nanostructures are developed based on ZnSe with lateral extensions down to 35 nm. Dry etching using Ar+ ions is found to generate very smooth etch surfaces, while the photoluminescence efficiency of narrow wires is much higher in wet chemically etched structures. As a first application of deep etched nanostructures, index coupled distributed feedback laser structures of second order are realized with periods down to 185 nm on the base of (Cd, Zn)Se/ZnSe/(Mg, Zn)(Se, S) vertical waveguide heterostructures. A clear correlation between the resonator period and the emission wavelength is observed, indicating a high coupling coefficient of the structures. For optical pumping using a pulsed NJaser, the laser threshold at room temperature is about 100 kW/cm2.

Photoluminescence blueshift induced by reactive ion etching of strained CdZnSe/ZnSe quantum well structuresStresses and strains in lattice-mismatched stripes, quantum wires, quantum dots, and substrates in Si technology Fabrication of nanostructures in AlGaSb/InAs using electron-beam lithography and chemically assisted ion-beam etching J.

One of the first MEMS products -the pressure sensor -has still room for innovation. We report a completely new pressure sensor generation based on a novel surface micromachining technology. Using porous silicon the membrane fabrication can be monolithically integrated with high synergy in an analogidigital semiconductor process suited for high volume production in an IC-fah. Only two mask tayers and one electrochemical ctching step are inserted at the beginning of a standard IC-process to transform the epitaxial silicon layer from the electronic process into a monocrystalline membrane with a vacuum cavity under it. Fig. 2: Pressure sensor membmne with vucuum cavity under it and implantedpiezzo resistors bn top.FABRICATION Fig, 1: Mtnihmnefabricatton iechnolo,y: (a) conventional hulk niicromachinirg wifh KUH etching and glass bonding to fabricate a membrnne over a 1-efirence vacuum. (b) using porous silicon technology a monoc ysiallinr membrarre i s jix-ied bj? eppita.xiul layer growth. The porous silicon is converted in a vucuiim caviy by sintering in H2 ntmosphere.The epitaxial layer is dcposited on a porous silicon layer. The cavity is formed by subsequent thermal rearrangement of this porous silicon during the epitaxial growth process and thc following high temperature difision processes [I]. The enclosed hydrogen in the cavity during the epitaxial deposition diffuses out, but no other gases can diffuse in. This leads to a good reference vacuum in thc cavity. The square membrane is deflected by 0.7 pm / bar. It is mcchanically robust against overload because of the ''floor stopper" when it touches the bottom of the cavity. A 1 bar sensor is overload proof to more than 60 bar. The signal is sensed by a piezoresistive Wheatstone bridge, which is a measurement principle with better linearity compared to capacitive sensors. The piezoresistors are fabricated using the same diffusion layers as the electronic circuit to achieve good matching properties. The bridge signal of 55 mV / bar is ampIified by the surrounding electronics. The mixedsignal semiconductor process is suited for the automotive temperature range of -40 .. +I40 "C. The circuit is designed to be ESD and EMC proof. TRANSDUCERS'OSThe 13th lnremational ConCerencc on Solid-State Sensors, Actuators and Microsystems, Seoul, Korea, June 5-9,2005 0-7803-8952-2/0.5/$20.00 0 2 0 0 s IEEE. 35

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