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We report the fabrication and characterization of highly dense field-effect-transistor (FET) arrays based on single-walled carbon nanotubes (SWCNTs). The nanotubes were sorted according to the electronic type by using density gradient ultracentrifugation (DGU). By employing dielectrophoresis (DEP), SWCNTs with enriched semiconducting (sc) content were systematically integrated as active elements into FETs. The performance of air-operating FETs was addressed via an extended statistic study involving both electrical and structural analyses. The competitive impact of nanotube purity and assembly as well as the metal electrode composition and a thermal treatment on the final device performance was shown. Regardless of the used sc-content, the device-to-device consistency was improved via employing annealing up to 250 °C for 1 h in a vacuum. The observed clockwise hysteresis, known so far only in connection with CNT–FETs built on ferroelectric substrates as well as electrolyte gated CNT–FETs, was found to reverse upon annealing. Moreover, a simple approach in producing air-stable ambipolar transistors is pointed out only via change of the adhesion layer for the Pd electrodes. The annealing study, repeated on such systems, supports the previous results and provides complementary information via a reliable monitoring of the off-state. Indications for a doping-like effect, which partially compromises the device performance in terms of threshold voltage shifts and increased off-state currents, are revealed and discussed.

The objective of this work is to study the optical and electrical properties of tantalum nitride and tantalum barrier thin films used against copper diffusion in Si in integrated circuits using spectroscopic ellipsometry in the VUV and UV–visible range. Single layers of tantalum nitride and bilayer films of Ta/TaN were produced by reactive magnetron sputtering on Si(100) substrates covered with a native oxide layer. Ellipsometric measurements were performed in the energy range from 0.73–8.7 eV and the dielectric functions were simulated using Drude–Lorentz model and effective medium approximation (EMA) in order to obtain information regarding film thickness, film composition, free carrier plasma energy, mean relaxation time and electrical resistivity. The film thickness clearly affects the electrical resistivity and the electron mean free path. It was observed that for films of Ta on TaN even after maintaining the deposition condition suitable for the β-phase of Ta, it turned out to be a mixture of α- and β-phases with higher contribution of the α-phase. It is shown that even a very small intermixture of two different phases of Ta can be determined accurately using ellipsometry. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

A low temperature direct bonding process with encapsulated metal interconnections was proposed. The process can be realized between silicon wafers or silicon and glass wafers. To establish well-insulated electric connection, sputtered aluminum film was patterned between a bottom thermal SiO2and a top PE-SiO2; the consequential uneven wafer surface was planarized through a chemical mechanical polishing (CMP) step. Benefit from this smooth surface finish, direct bonding is achieved at room temperature, and a general yielding rate of more than 95% is obtained. Test results confirmed the reliability of the bonding. The main advantages of this new technology are its electric connectivity, low thermal stress and hermeticity. This process can be utilized for the packaging of micro electro mechanical system (MEMS) devices or the production of SOI wafers with pre-fabricated electrodes and wires.A low temperature direct bonding process with encapsulated metal interconnections was proposed. The process can be realized between silicon wafers or silicon and glass wafers. To establish well-insulated electric connection, sputtered aluminum film was patterned between a bottom thermal SiO2and a top PE-SiO2; the consequential uneven wafer surface was planarized through a chemical mechanical polishing (CMP) step. Benefit from this smooth surface finish, direct bonding is achieved at room temperature, and a general yielding rate of more than 95% is obtained. Test results confirmed the reliability of the bonding. The main advantages of this new technology are its electric connectivity, low thermal stress and hermeticity. This process can be utilized for the packaging of micro electro mechanical system (MEMS) devices or the production of SOI wafers with pre-fabricated electrodes and wires.

nBu3P‐Silver(I)‐β‐Diketonates: Synthesis, Gas Phase Studies, and their Use as CVD‐Precursors

Tri‐n‐Butyl‐Phosphane Silver(I) Complexes with Carboxylate‐, Tropolonate‐ or N‐Hydroxyphthalimide Building Blocks; Synthesis and their Use as Spin‐on Precursors

Die Reaktion von [(η2‐Me3SiC≡CSiMe3)CuBr]2(1) mit zwei Äquivalenten an [M(O∩O)] [M = Na, Ag; O∩O = Acetylacetonat, acac, 2a/ 3a; = 1, 1, 1, 5, 5, 5‐Hexafluoroacetylacetonat, hfac, 2b/ 3b; = 2, 2, 6, 6‐Tetramethyl‐3, 5‐heptandionat, tehe, 2c/ 3c; = 1, 3‐Diphenyl‐1, 3‐propandionat, dipa, 2d/ 3d; = 2‐Methyl‐4‐pyronat, mepy, 2e/ 3e; = Troponolat, trop, 2f/ 3f) führt zu [(η2‐Me3SiC≡CSiMe3)Cu(O∩O)] (4a, acac; 4b, hfac; 4c, tehe; 4d, dipa; 4e, mepy; 4f, trop), welche durch Umsetzung mit PR3(R = C6H4CH2NMe2‐2)3(5) unter Verdrängung von Me3SiC≡CSiMe3die Phosphan‐Kupfer(I)‐β‐Diketonato‐Komplexe [(R3P)Cu(O∩O)] (O∩O = acac, 6a; = hfac, 6b; = tehe, 6c; = dipa, 6d; = mepy , 6e; = trop, 6f) ] ergeben. Die Komplexe 6a— 6fwerden auch gebildet, wenn man 5mit äquimolaren Mengen an CuCl (7) und dann mit Na(O∩O) (2) zur Reaktion bringt. Verwendet man an Stelle von 2bzw. 3das Silbersalz Ag2(O2∩O2) (O2∩O2= 1, 4‐Benzochinoat, benz, 9a; = 1, 4‐Anthrachinoat, anth, 9b), so werden homobimetallische Komplexe des Typs [(R3P)CuO2∩O2Cu(PR3)] (O2∩O2= benz, 10a; = anth, 10b) erhalten, in denen zwei Kupfer(I)‐Phosphan‐Bausteine über π‐konjugierte organische O2∩O2‐Brücken miteinander verknüpft sind.

Abstract. Variable angle spectroscopic ellipsometry (VASE) and ellipsometric porosimetry (EP) have been used to study the effect of treatment with hexamethyldisilazane (HMDS) on the porosity of silica xerogel films. Chemical modification of the surface with HMDS was found to reduce the porosity by ~15%. This reduction was connected with changes which occur in the silica network, with further condensation or the reaction between neighbouring trimethylsilyl (TMS) surface groups being possible causes.

Abstract:  Frequency selective vibration sensors for wear state recognition have been fabricated using surface near silicon bulk micromechaning (SCREAM). Capacitive detection combs convert the mechanical vibration into an electrical signal. Operating in a frequency selective resonant mode allows direct extraction of spectral information without Fourier transformation. To enlarge the measurement range they provide a frequency tuning capability by stress-stiffening which is achieved by electrostatic forces. Using force enhancing lever mechanism frequency variation of up to 100% of the base frequency has been measured with tuning voltages of 50 V. By arranging multiple cells with stepped base frequencies and overlapping tuning ranges the covered frequency range is widely extended. A fabricated array of ten cells is capable to continuously scan the range from 1 to 10 kHz.

The properties of surface and buried interface silicon oxide layers in low- and high-temperature SiSi bonded wafers, were investigated using infrared spectroscopy, spectroscopic ellipsometry (SE) and high resolution transmission electron microscopy (HRTEM). Infrared transmission spectra show the absorption by SiOSi vibrations originating from surface and interface silicon oxide. To distinguish the contribution of surface and buried interfaces oxide in the spectra, the surface oxide was removed by chemical etching. The interface oxide thickness was calculated from curve fitting of infrared transmission spectra of the etched bonds. An excellent agreement of values of the interface oxide thicknesses determined using this method with those obtained from HRTEM measurements was found. The behaviour of longitudinal and transversal optical (LO and TO) phonons in surface silicon oxide was analysed. The frequency position of TO and LO modes shifts towards higher energy and the LO-TO splitting decreases upon annealing. This behaviour can be explained in terms of a thermal relaxation model.

Abstract:  The present study is focused on the development of a gas sensor for application in a high temperature environment. The sensor has been realised using thin films prepared on silicon substrates including a high temperature stable heating and wiring system. TiO2 acts as sensitive layer. Measurements have been carried out in synthetic gas mixtures as well as in gases in a given application. Neural networks and multivariate data analysis have been used for determining the gas concentrations. The capability to detect CO, NO x , and toluene is shown.

The high precision accelerometer consists of 5 silicon wafers and packages by silicon fusion bonding. The sensor has a capacitance measuring principle and works in an open loop or closed loop operation mode. The etching process for the realization of thin beams and seismic mass, the silicon fusion bonding and the metallization process are described.

Glucuronidation of [3H]acetaminophen (APAP) was studied in rat liver preparations. Both Triton X-100 and UDP-N acetylglucosamine (UDPAG) activated 3- to 4-fold the glucuronidation of APAP by liver homogenates or microsomes. Prednisolone inhibited microsomal glucuronidation of APAP, yielding apparent noncompetitive kinetics in native and in UDPAG-activated microsomes. Studies with UDPAG-activated microsomal preparations show that many drugs can inhibit glucuronidation of APAP markedly; among the most poten inhibitors are: morphine, dicumarol, hydroxyzine, phenolphthalein, chloramphenicol and tetracycline.

A simple method was developed for the routine monitoring of daunorubicin (DR) or adriamycin (ADR) and of their chief fluorescent metabolites in plasma of cancer patients. The plasma samples were treated with ethanol: hydrochloric acid mixture, following which the drug and its metabolites, released to the 40,000 g supernatant, were analyzed by HPLC. A µ-bondapak-phenyl column was used and an isocratic mobile phase consisting of acetonitrile in 0.1 M ammonium-formate bufter at pH 4.0. Avarage recovery of all the tested compounds within the concentration range of 17–3,450 pmol/ml plasma was 108±5% (mean±SD).

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Aus geeignetem p-Silizium mit kleinen Borverteilungsschwankungen konnte hochohmiges n-Silizium mittels Neutronendotierung hergestellt werden. Dieses n-Silizium diente zur Herstellung von Detektorstrukturen mit implantierten Kontakten. Diese Detektoren sind fur den Nachweis von Photonenstrahlung geeignet.An Hand der beschriebenen phyiskalischen Grundlagen der Neutronendotierung und der Detektorparameter werden die Wege zur Verbesserung der spektrometrischen Eigenschaften von Detektoren aus neutronendotiertem Silizium diskutiert.

The effect of hydrogen ion activity (pH) on the degree of meperidine sequestration in gastric contents was studied in 15 patients. Those patients with higher gastric juice cH+(lower pH) showed greater accumulation with time. At a cH+more than 10,000 nmol/l, (pH < 5) concentration usually reached 100 μg/ml within the 60-minute period after administration of 200 mg of meperidine. When cH+was less than 100 nmol/l (pH > 7) gastric concentrations remained low, being only slightly greater than those of plasma. Oral administration of antacid may be a practical method for preventing sequestration of meperidine in gastric juice.