Der Zweiphasenfluss eines Gas‐flüssig‐segmentierten Flussreaktors mit mehreren Temperaturzonen ermöglicht sowohl das schnelle Mischen von Reagentien als auch enge Verweilzeitverteilungen. Das Reaktordesign...
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Der Zweiphasenfluss eines Gas‐flüssig‐segmentierten Flussreaktors mit mehreren Temperaturzonen ermöglicht sowohl das schnelle Mischen von Reagentien als auch enge Verweilzeitverteilungen. Das Reaktordesign erlaubt die Herstellung kolloidaler CdSe‐Quantenpunkte mit hervorragenden Größenverteilungen bei hoher Temperatur. Dies schildern K. F. Jensen, M. G. Bawendi et al. in ihrer Zuschrift auf S. 5583 ff. (Die Autoren danken Jane Rempel für die Hilfe bei der Erstellung des Titelbilds.)
A synchronization scheme for extraction of low jitter RF-signals from optical pulse trains, which is robust against photo-detector nonlinearities, is described. Sub-100 fs timing jitter between the extracted RF-signal...
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The transport properties of polycrystalline Si/sub 0.8/Ge/sub 0.2/ thin films are studied for their potential applications in micro power generators. These thin films are deposited by low-pressure chemical deposition ...
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The transport properties of polycrystalline Si/sub 0.8/Ge/sub 0.2/ thin films are studied for their potential applications in micro power generators. These thin films are deposited by low-pressure chemical deposition (LPCVD). The doping is carried out by boron and phosphorus ion implantation, followed by annealing in nitrogen ambient. The concentration of boron and phosphorus 4.3x10/sup 19/ cm/sup -3/, and 8.7x10/sup 19/ cm/sup -3/, respectively. The thermoelectric transport properties of these thin films are measured, including electrical conductivity, Seebeck coefficient, and thermal conductivity. The electrical conductivity is measured by a 4 point-probe method. The Seebeck coefficient is measured by applying a temperature gradient along the in-plane direction, and evaluating the resulting voltage. The thermal conductivity is measured by a 3/spl omega/ method in the cross-plane direction.
A high-resolution accelerometer with a bulk-micromachined silicon proof mass and an interferometric position sensor was developed for measuring vibratory accelerations. The interferometer consists of interdigitated ri...
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A high-resolution accelerometer with a bulk-micromachined silicon proof mass and an interferometric position sensor was developed for measuring vibratory accelerations. The interferometer consists of interdigitated ringers that are alternately attached to the proof mass and support substrate. Illuminating the fingers with coherent light generates a series of diffracted beams. The intensity of a given beam depends on the out-of-plane separation between the proof mass fingers and support fingers. Proof masses with mechanical resonances ranging from 80 Hz to 1 kHz were fabricated with a two mask process involving two deep reactive ion etches, an oxide etch stop, and a polyimide protective layer. The structures were packaged with a laser diode and photodiode into 8.6-cm/sup 3/ acrylic housings. The 80-Hz resonant proof mass has a noise equivalent acceleration of 40 ng/rt Hz and a dynamic range of 85 dB at 40 Hz.
For nominally high-symmetry cylindrical-shaped vertical quantum dots, we show that Hund’s first rule is not violated if maxima appear in the 0-T addition energy spectra at positions other than when the shell is half ...
For nominally high-symmetry cylindrical-shaped vertical quantum dots, we show that Hund’s first rule is not violated if maxima appear in the 0-T addition energy spectra at positions other than when the shell is half filled. For the third shell, a minimum at N=7 electrons followed by a maximum at N=8 or 9 electrons is the only clear signature of sequential spin alignment up to half shell occupation. We demonstrate that the filling of this shell and the consequent spectral shape for realistic dots are quite rich and varied.
On-chip optical clock distribution is being investigated as a future means to increase clock speed and reduce clock power. While extremely small skew in the arrival of an on-chip optical signal can be achieved, the co...
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ISBN:
(纸本)0780366883
On-chip optical clock distribution is being investigated as a future means to increase clock speed and reduce clock power. While extremely small skew in the arrival of an on-chip optical signal can be achieved, the conversion of the optical signal to a local electrical clock may be subject to substantial variation. A baseline receiver circuit has been designed and fabricated. We find that sensitivity to device and operating condition variation reintroduces substantial clock skew. Future optical on-chip clock design approaches must take such variation sources into account.
Low temperature, wafer-level bonding offers several advantages in MEMS packaging, such as device protection during aggressive processing/handling and the possibility of vacuum sealing. Although thermocompression bondi...
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Low temperature, wafer-level bonding offers several advantages in MEMS packaging, such as device protection during aggressive processing/handling and the possibility of vacuum sealing. Although thermocompression bonding can be achieved with a variety of metals, gold is often preferred because of its acceptance in die bonding [1] and its resistance to oxidation. This study demonstrates that the simultaneous application of moderate pressure (0.5 MPa) and temperature (300°C) produces strong wafer-level bonds. A four-point bend-delamination technique was utilized to quantify bond toughness. Test specimens exhibited constant load versus displacement behavior during steady state crack propagation. Two distinct fracture modes were observed: cohesive failure within the Au and adhesive failure at the Ti-Si interface. The strain energy release rate for Au-Au fracture was found to be higher than that associated with Ti-Si fracture, consistent with the greater plastic deformation that occurs in the metal during fracture.
Low temperature, wafer-level bonding offers several advantages in MEMS packaging, such as device protection during aggressive processing/handling and the possibility of vacuum sealing. Although thermocompression bondi...
Low temperature, wafer-level bonding offers several advantages in MEMS packaging, such as device protection during aggressive processing/handling and the possibility of vacuum sealing. Although thermocompression bonding can be achieved with a variety of metals, gold is often preferred because of its acceptance in die bonding [1] and its resistance to oxidation. This study demonstrates that the simultaneous application of moderate pressure (0.5 MPa) and temperature (300°C) produces strong wafer-level bonds. A four-point benddelamination technique was utilized to quantify bond toughness. Test specimens exhibited constant load versus displacement behavior during steady state crack propagation. Two distinct fracture modes were observed: cohesive failure within the Au and adhesive failure at the Ti-Si interface. The strain energy release rate for Au-Au fracture was found to be higher than that associated with Ti-Si fracture, consistent with the greater plastic deformation that occurs in the metal during fracture.
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