Surgical site infection (SSI) surveillance is performed using a variety of methods with unclear performance characteristics. We used claims data to identify records for review following hysterectomy and colorectal surgery. Claims-enhanced screening identified SSIs missed by routine surveillance and could be used for targeted chart review to improve SSI detection.

Extended abstract of a paper presented at Microscopy and Microanalysis 2009 in Richmond, Virginia, USA, July 26 – July 30, 2009

The evolution of microstructure during Au-mediated solid phase epitaxial growth of a SiGe alloy film on Si(001) (c-Si) was investigated by in situ resistance measurements, X-ray diffraction, conventional and high-resolution transmission electron microscopy, and chemical microanalyis. Annealing a-Ge/Au bilayers on c-Si to temperatures below 120°C caused changes primarily in the microstructure of the Au film. Increases in temperature to ≃150°C resulted in the diffusion of Ge through the grain boundaries of Au. The Au, displaced by crystalline Ge at the grain boundaries, diffused along columnar voids of amorphous Ge (a-Ge) leading to the formation of Au-rich crystallites in the top layer. Results indicate that the Ge that had reached the Au/c-Si interface grew epitaxially on c-Si at temperatures below 150°C. As the temperature was further increased, some Si from the substrate dissolved into Au and got incorporated in the growing epilayer. At 310°C, the initial Au film was displaced completely by a laterally continuous Siξ Gei.ξ (ξ ∼ 0.2) epilayer whose thickness was limited by that of the initial Au film. Twins, and residual amounts of Au near the SiGe/c-Si interface, were the predominant defects observed in the SiGe epilayer.

There exists considerable interest in the synthesis of nanocrystalline SiC particles embedded in an a-SixC1−x:H matrix. This study investigated the formation of nanocrystalline SiC by annealing a non-equilibrium a-Si0.35C0.65 alloy sputter deposited onto oxidized (100) Si. Evolution of the microstructure was characterized by thin film sheet resistance measurements, glancing angle X-ray diffraction (GAXRD) and transmission electron microscopy (TEM). It was found that films annealed at temperatures below 850°C remained amorphous. Annealing at temperatures above 850°C resulted in the formation of SiC nanocrystallites, as revealed by GAXRD and TEM. The electrical conductivity also showed an abrupt increase around 950°C. Prolonged annealing resulted in a further increase in conductivity, implying that the transformation continued. Annealing at 1100°C for 3 hours increased the film conductivity by two orders of magnitude relative to the as-deposited film.

In this study, we report a new wafer bonding technique for the integration of GaAs- and InP-based optical devices with prefabricated Si electronic devices in hybrid circuit technology. This technique uses a Au-Ge eutectic alloy as the bonding materials between GaAs and Si wafers, and between InP and Si wafers. This process takes advantage of the low temperature solid-state reactions at GaAs/Au-Ge, InP/Au-Ge, and Si/Au-Ge interfaces. The bonding was carried out by annealing the samples at 280–300°C in an alloying furnace. The reliability of the joined wafers was evaluated by both cleavage test and standard thermal cycling test. The joining interfaces were characterized by scanning electron microscopy and transmission electron microscopy. The results reveal that the bonding is achieved by low temperature reactions at the GaAs/Au-Ge and InP/Au-Ge interfaces as well as solid-phase epitaxial regrowth at the Si interfaces. The joined structure has very good integrity.

In VLSI technology, there is interest in monitoring the sequence of phase formation of TiSi2 (c-Ti ⇒ a-TiSi ⇒ C49 TiSi2 ⇒ C54 TiSi2), with the prospect of reducing the temperature of formation of the stable C54 TiSi2 phase. In this study, phase formation characteristics of TiSi2 during rapid thermal annealing(RTA) of Ti-Si bilayers are investigated by means of in situ four point probe resistance measurements. Ex situ X-ray diffraction(XRD) was used for phase identification and characterization. Results indicate that the same multi-step sequence of transformations precede the formation of the C54 TiSi2 phase for heating rates from 1°C/s to 100°C/s. Also, all intermediate and metastable phases which occur at l°C/s also occur at 100°C/s. Temperature dependence and kinetics of the C49 TiSi2 and the C54 TiSi2 phase formation were studied over a wide range of heating rates. Activation energies estimated for the two processes were ∼2eV and ∼5eV respectively. Finally, a new Electrical Thermal Annealing(ETA) technique for heating at rates up to 30000°C/s is introduced. Preliminary in situ resistivity measurement results of TiSi2 formation at these high heating rates are also presented.

The kinetics and mechanism of the C49 to C54 TiSi2 polymorphic transformation have been investigated in a temperature range from 660 to 720°C using in situ sheet resistance measurement and transmission electron microscopy. The kinetics results were correlated with the microstructural changes during the phase transformation. The main structural characteristics demonstrating the mechanism of the transformation were established by examining the nucleation and growth of the C54-TiSi2 in the polycrystalline C49-TiSi2 thin films. It was found that the C54 nuclei predominantly formed at grain edges (three-grain junctions) of the C49 phase and grew very fast by moving its incoherent interphase boundaries. Preliminary results have not revealed rigorous orientation relationships between the two phases. It is suggested that the C49 to C54 structural transition is massive in nature.

Solid phase epitaxial (SPE) growth of SixGei1-x alloys on Si (100) was achieved by thermal annealing a-Ge/Au bilayers deposited on single crystal Si substrate in the temperature range of 280°C to 310°C. Growth dynamics was investigated using X-ray diffraction, Rutherford backscattering spectrometry, and cross-sectional transmission electron microscopy. Upon annealing, Ge atoms migrate along the grain boundaries of polycrystalline Au and the epitaxial growth initiates at localized triple points between two Au grains and Si substrate, simultaneously incorporating a small amount of Si dissolved in Au. The Au is gradually displaced into the top Ge layer. Individual single crystal SixGei1-x islands then grow laterally as well as vertically. Finally, the islands coalesce to form a uniform layer of epitaxial SixGe1-x alloy on the Si substrate. The amount of Si incorporated in the final epitaxial film was found to be dependent upon the annealing temperature.

Initial stage of growth of metastable titanium disilicide (C49-TiSi2) was investigated by annealing Ti/doped polycrystalline Si bilayers deposited on oxidized Si wafers at 530°C and at a constant heating rate of 10°C/min. Morphological evolution of the C49-TiSi2 phase was studied by cross-sectional transmission electron microscopy (XTEM) and local chemistry was probed with a scanning transmission electron microscope (STEM) equipped with a nanoprobe. At the early stage, the C49-TiSi2 phase nucleates discontinuously along the amorphous silicide (a-TiSix )/crystalline Si (c-Si) interface and then exhibits simultaneous lateral growth and vertical growth. The results are interpretated using a model based upon preferential Si diffusion along interphase boundaries to the growth front.

We have studied interdiffusion and phase relations in two titanium aluminide/Nb/titanium aluminide composite structures at 1100 °C using solid state diffusion approach. The composite structures were prepared with two practical intermetallic alloys, γ (Ti-48Al-2Nb-0.3Ta, in at.%) alloy and super-α2 (Ti-25Al-10Nb-3V-1Mo, in at.%) alloy, and pure Nb sheet by diffusion bonding technique. The interfacial microstructures evolved during thermal diffusion annealing were characterized using optical microscopy, SEM, TEM and X-ray diffraction. The effect of Nb on the phase stabilities of two intermetallic alloys and the phase relations among different phases formed in the diffusion zone due to interdiffusion were analyzed in terms of rules of diffusion paths on the basis of the observed diffusion structures and experimental diffusion paths.

The formation of suicides during the thermal reaction of Ti/polysilicon bilayers has been investigated using both in-stu four point sheet resistance measurements and ex-situ measurements including X-ray diffraction, cross-sectional transmission electron microscopy and Auger electron spectroscopy. For a series of samples annealed at a ramp rate of 10°C/min the following sequence of changes in the bilayers occurred. At temperatures exceeding 350°C and prior to the silicidation oxygen from the vacuum system diffuses into the Ti film forming a solid solution of Ti(O) with O levels up to 20 %. An amorphous TixSiy layer is the first major suicide reaction observed at temperatures near 440°C. The first major crystalline phase is observed at 500°C and identified as C49 TiSi2. This phase was found to coexist at these temperatures with the partially consumed Ti(O) and the amorphous TixSiy layers. Further annealing above 700 °C results in the final structural transformation from C49 TiSi2 to C54 TiSi2.

Interfacial microstructure of In/Pd ohmic contacts to n-GaAs was studied by various X-ray diffraction techniques and secondary ion mass spectroscopy (SIMS). Analysis of this interface after various annealing showed that In1-xGaxAs compounds are formed at the interface and the composition of these compounds depends upon the annealing temperature. As the temperature increases, the stoichiometry of the Inrich compounds tends toward higher concentrations of Ga. The low contact resistance is achieved by dividing the Schottky barrier between metal and GaAs into two barriers due to metal/Inl-xGaxAs and In1-xGaxAs/GaAs. The barrier due to In1-xGaxAs/GaAs is believed to be the main limiting factor in lowering of contact resistance. The observed ohmic behavior for sample annealed at 500°C for 20 s is attributed to the further reduction of this barrier.