摘要:

An ultraviolet-sensitive photodetector based on the metal-semiconductor-metal structure has been fabricated on a chemical-vapor-deposited diamond thin film grown on a silicon substrate. Device processing techniques employed include maskless laser writing lithography, image reversal processing and sacrificial layer inclusion, which resulted in devices with an electrode finger separation of only 2.5 &mgr;m. This allows for a low operating voltage of only 5 V, which is very much lower than what has been achieved so far. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120992

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

We present and experimentally demonstrate a traveling wave photodetector adapted to the detection of optically carried microwave signals. The synchronous propagation of the detected modulated laser beam with the photogenerated microwave signal is obtained with a diffraction grating. This concept provides a large detection volume which could be suitable for the optical generation of high power/large dynamic range microwave signals. The operating principle of the device is detailed and experimentally demonstrated, over a 0–5 GHz bandwidth, using a coplanar metalsemiconductor-metal waveguide on a GaAs molecular beam epitaxially grown layer. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120993

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

A coherent fiber image guide comprised of individual fibers with a core diameter as small as 250 nm is reported. By using optical fibers with a very large difference between the indices of refraction of the core and cladding materials, efficient containment of light inside the core is achieved even for submicron core diameters, without the need for metallization. Images with subwavelength resolution are obtained with such an image guide. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120994

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Following the earlier observation of active mode locking in the high field region of the Voigt configuredp-Ge intervalence band laser, presently mode locking in thelowfield region is also reported. The experimental results on the effective small signal gain for active- as well as for self-mode locked operation are given. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120995

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

The correlation between the nonuniformities of plasma parameters (i.e., floating potential) and the induced charging onto the surface of oxide-covered unpatterned 4 in. Si wafers exposed toO2electron cyclotron resonance (ECR) plasma is investigated. Wafers covered with a 1000 Å oxide layer were exposed to the ECR plasma under nonuniform conditions, and the induced surface charge was mapped on the wafers using contact potential difference technique. Floating potential profiles were monitored using a Langmuir probe. Experimental data indicate that the magnitude of the surface charge is proportional to the deviation of the floating potential from its surface-averaged potential. These results were compared to location of the damage of metal-oxide-semiconductor capacitor test structures exposed to same plasmas. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120996

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

This letter describes a technique for measuring the ion current at a semiconductor wafer that is undergoing plasma processing. The technique relies on external measurements of the radio-frequency (rf) current and voltage at the wafer electrode. The rf signals are generated by the rf bias power which is normally applied to wafers during processing. There is no need for any probe inserted into the plasma or for any additional power supplies which might perturb the plasma. To test the technique, comparisons were made with dc measurements of ion current at a bare aluminum electrode, for argon discharges at 1.33 Pa, ion current densities of1.3–13 mA/cm2,rf bias frequencies of 0.1–10 MHz, and rf bias voltages from 1 to 200 V. Additional tests showed that ion current measurements could be obtained by the rf technique even when electrically insulating wafers were placed on the electrode and when an insulating layer was deposited on the electrode.

ISSN:0003-6951    

DOI:10.1063/1.121032

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Numerical simulations were performed to predict the performance of microwave plasma reactors with various reactor geometries. The simulations include the calculation of the electric field distribution using the finite integration theory and the determination of the plasma density distribution based on a breakdown field algorithm. One reactor geometry with a cavity having the shape of a rotational ellipsoid turned out to be very promising. The electric field within this cavity exhibits two pronounced maxima at the two focal points of the ellipsoid. By coupling microwave energy into one maximum via an antenna, large electric field strengths can be generated in the counter maximum. This effect has been used to excite intense discharges that are very stable, spatially extended, homogeneous, and free from wall contact. These discharges were employed for the chemical vapor deposition of large area diamond wafers. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120997

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Preamplification of mechanical signals in external force detection systems can improve overall sensitivity in a case where sensitivity is limited by secondary detection noise. We report experimental data on degenerate and nondegenerate mechanical parametric amplification in GaAs piezoresistive atomic force microscopy cantilevers due to an inherent mechanical nonlinearity. The mechanical nonlinearity is estimated to be a result of curvature at the cantilever base. Characteristics of parametric amplification such as phase sensitive gain, small signal gain, gain saturation, and self-oscillation have been studied. A small signal phase sensitive gain of 19.5 dB was observed for the degenerate parametric amplifier. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120998

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

A novel microstructure is formed on the single crystal surfaces of the oxide superconductorBa0.6K0.4BiO3(BKBO). Micron-sized barium islands periodically grew on the mother crystal during electrocrystallization of BKBO. Experimental analysis suggested the relation of this unusual microstructure to the Liesegang rings well-known for a crystal growth in gels. The present discovery provides a potential technology for fabricating microstructures on substrates of solids. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120999

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

EpitaxialAlxGa1−xNfilms have been grown onc-cut sapphire substrates at 800 °C and10−2 TorrN2by pulsed laser deposition (PLD) using a KrF laser. Throughout the composition range fromx=0to 0.6, the films show epitaxial patterns in reflection high-energy electron diffraction, in agreement with the results from x-ray diffraction. The lattice constants of the films vary linearly withx. The composition dependence of the band gaps of the films deviates from linearity and bows downward. This letter reports the application of PLD to controlling the lattice constant and band gap by varying the proportion of AlN and GaN in the target mixture. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121033

出版商:AIP    

年代:1998

数据来源: AIP