We demonstrate that the temperature coefficient of resistance (TCR) of NiCr thin film resistors can be effectively controlled by changing the film thickness over a certain range. We have observed a direct dependency between TCR and sheet resistance, which can be expressed by the equation: TCR(in ppm/C)=525*exp(-0.01*sheet (in Ohms/sq)). This behavior can be explained by considering the transition from a bulk conductivity mechanism to a mechanism dominated by charge carrier creation and tunneling between metallic islands.
Time-Dependent Dielectric Breakdown (TDDB) data for very thick (8um) silica-based dielectrics is reported at relatively low fields (< 5MV/cm) but at extremely high voltages (up to 4000V). TDDB data was taken across a wide range of dielectric thicknesses ranging from 38Å to 8μm (80,000Å). Consistent with the TDDB results generally reported for thin films, a thickness-independent effective dipole moment of ~13eÅ was concluded from the testing data. TDDB data is also presented for stacked dielectrics structures (Nitride/Silica) which tend to show a strong polarity dependence, depending on whether electron injection is into the nitride or oxide layer. While the time to failure is polarity dependent, the effective dipole moment is independent of polarity. [
In this paper we have developed a model to obtain drain current (ID) degradation at all transistor operating modes (linear, saturation and sub-threshold) during NBTI stress based on threshold voltage (VT) and mobility (μ) degradation. This model provides a compact way to comprehend NBTI induced drain current degradation for transistors subject to multiple operating modes (e.g., dynamic voltage scaling, active/standby modes).
We describe a second generation central receiver solar thermal power conversion system that may offer more cost effective plant operation than plants presently under study for early POCE development.It is, however, technologically more risky.Our concept uses formed focusing heliostats more extensively, secondary reflection to a boiler at ground level, a flux concentrator at the boiler entrance, transpiration cooling of the boiler heat exchanger, and high energy density storage devices to smooth plant output. We report tests of some of the critical subcomponents in an actual intense solar environment. Finally, we summarize the potential system advantages for each element of the second generation plant.
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