Organic Field-Effect-Transistors with Pentacene for radio-controlled-price-tag applications

This letter presents organic thin-film-transistors (OTFT) using the small organic molecule Pentacene targeting applications like radio controlled identification tags. Simple OTFTs as well as inverter circuits based on a pconducting silicon wafer substrate are presented. Comparing PECVD oxide and LTO as dielectric, only LTO deposited layers provide sufficient electrical stability. PECVD oxides show defects called “pin-holes", leading to short circuiting through the gate dielectrics. OTFTs of L=1µm/W=1000µm were prepared providing Ids = 61µA at –40Vds and –40Vgs, a subthreshold slope of 10.3 V/dec and an on-offratio of 102. The inverter circuits using insulated gate contacts switch from VA=–10V to VA=–3V output voltage when the input voltage is varied from VE=0V to VE=–8V at a supplied voltage of VB=–10V

Macro-modelling via radial basis functionen nets

By the rising complexity and miniaturisation of the device's dimensions, the density of the conductors increases considerably. Referring to this, locally transient interactions between single physical values become apparent. Therefore, for the investigation and optimisation of integrated circuits it is essential to develop suitable models and simulation surroundings which allow for memory and timeefficient calculation of the behaviour. By means of the dynamic reconstruction theory and the radial basis functions nets the so-called black box models are provided. The description of black box models is derived from the input and output behaviour or so-called time series of a dynamic system. Concerning the time series, the black box model adapts its parameters via the extended Kalman filter. This paper provides a modelling approach that enables fast and efficient simulations.BMBF/01M3169 EInfineon Technologies AG/01M 3169

Sortase A Substrate Specificity in GBS Pilus 2a Cell Wall Anchoring

Streptococcus agalactiae, also referred to as Group B Streptococcus (GBS), is one of the most common causes of life-threatening bacterial infections in infants. In recent years cell surface pili have been identified in several Gram-positive bacteria, including GBS, as important virulence factors and promising vaccine candidates. In GBS, three structurally distinct types of pili have been discovered (pilus 1, 2a and 2b), whose structural subunits are assembled in high-molecular weight polymers by specific class C sortases. In addition, the highly conserved housekeeping sortase A (SrtA), whose main role is to link surface proteins to bacterial cell wall peptidoglycan by a transpeptidation reaction, is also involved in pili cell wall anchoring in many bacteria. Through in vivo mutagenesis, we demonstrate that the LPXTG sorting signal of the minor ancillary protein (AP2) is essential for pilus 2a anchoring. We successfully produced a highly purified recombinant SrtA (SrtAΔN40) able to specifically hydrolyze the sorting signal of pilus 2a minor ancillary protein (AP2-2a) and catalyze in vitro the transpeptidation reaction between peptidoglycan analogues and the LPXTG motif, using both synthetic fluorescent peptides and recombinant proteins. By contrast, SrtAΔN40 does not catalyze the transpeptidation reaction with substrate-peptides mimicking sorting signals of the other pilus 2a subunits (the backbone protein and the major ancillary protein). Thus, our results add further insight into the proposed model of GBS pilus 2a assembly, in which SrtA is required for pili cell wall covalent attachment, acting exclusively on the minor accessory pilin, representing the terminal subunit located at the base of the pilus

Telemetric surface acoustic wave sensor for humidity

Surface acoustic wave sensors consist of a piezoelectric substrate with metal interdigital transducers (IDT) on top. The acoustic waves are generated on the surface of the substrate by a radio wave, as it is well known in band pass filters. The devices can be used as wireless telemetric sensors for temperature and humidity, transmitting the sensed signal as a shift of the sensor’s resonance frequency

Inverter circuits on glass substrates based on ZnO-nanoparticle thin-film transistors

The integration technique and the properties of inverter circuits on glass substrates using ZnO nanoparticles as semiconductor material are presented. The inverter device consists of a switching and a load metal-insulator-semiconductor field-effect transistor with poly(4-vinylphenol) as the gate dielectric. Although the semiconductor is deposited by spin-coating of a colloidal ZnO dispersion and the process temperature is limited to 200 °C, the inverters show reasonable maximum peak gains at low power consumption. The maximum peak gain was 6 V/V, whereas the maximum static power dissipation density was less than 26 nW/microm2. Additionally, the influence of the geometry ratio as well as of the supply voltage on the device performance has been investigated. With regard to the optical characteristics, the proposed technique leads to circuits with an optical transmittance of up to 80%

Low temperature layer purification by pulsed UV-irradiation for flexible dye sensitized solar cells

The efficiency of dye sensitized solar cells (DSSCs) is strongly influenced by the quality of the front electrode. To remove dispersal additives and to enable sintering effects the TiO2 layer has to be heated up to 450°C for one hour. Nevertheless, for flexible DSSCs the process temperature is limited by the foil to about 150°C. Hence, a sintering of the particles is not possible and the cleaning effect is also declined, but both can be compensated with the development presented in this paper. This paper demonstrates that after 90 min of permanent intensive UV-irradiation nearly all additives are evaporated. Furthermore, to decrease the stress on the foil a pulsed UV-irradiation is performed and the pulse-pause-ratio optimized

Flexible electronics: Integration processes for organic and inorganic semiconductor-based thin-film transistors

Flexible and transparent electronics have been studied intensively during the last few decades. The technique establishes the possibility of fabricating innovative products, from flexible displays to radio-frequency identification tags. Typically, large-area polymeric substrates such as polypropylene (PP) or polyethylene terephthalate (PET) are used, which produces new requirements for the integration processes. A key element for flexible and transparent electronics is the thin-film transistor (TFT), as it is responsible for the driving current in memory cells, digital circuits or organic light-emitting devices (OLEDs). In this paper, we discuss some fundamental concepts of TFT technology. Additionally, we present a comparison between the use of the semiconducting organic small-molecule pentacene and inorganic nanoparticle semiconductors in order to integrate TFTs suitable for flexible electronics. Moreover, a technique for integration with a submicron resolution suitable for glass and foil substrates is presented