Typical Standard Uncertainty Research Articles

Modified Step-Up Method for Calibration of DC High-Voltage Dividers

The dc high voltage is usually measured with high-voltage divider which plays the role of the ratio standard linking the unknown high voltage to the well-known low-voltage standards. A step-up method had been proposed to calibrate the dividing ratios of the high-voltage dividers at nominal test voltage. The step-up technique has been newly modified for improving the transfer accuracy of reference values determined in voltage stack stage, with employing an additional source voltage monitoring device, and successfully applied to precisely determine the dividing ratios up to 100 kV. Typical standard uncertainty for the dividing ratios is estimated to be approximately $5 \times 10^{{ {-6}}}$ .

On-Wafer Measurement of Transistor Noise Parameters at NIST

The National Institute of Standards and Technology has developed the capability to measure noise parameters on a wafer in the 1-12.4-GHz range. The authors describe the measurement method and the uncertainty analysis and present results of measurements on a highly reflective transistor. Typical standard uncertainties are within the range of 20-25 K in T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">min</sub> , which is the minimum transistor noise temperature, and about 0.03 in the magnitude of Gamma <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">opt</sub> , which is the reflection coefficient for which T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">min</sub> occurs

Hot-electron attenuation lengths in ultrathin magnetic films

Ballistic electron emission microscopy (BEEM) is used to measure hot-electron transport across magnetic metal multilayers. Room temperature measurements in air have been carried out on Au/M/Si(100), Au/M/Au/Si(100), and Au/M/PtSi/Si diodes, that were sputter deposited at 175 or 300 K, where M is Co, Fe, Ni, Cu, or Ni81Fe19. Plots of log BEEM current versus M thickness are linear giving hot-electron (1.5 eV) attenuation lengths (ALs), for Au/M/Si diodes (M=Co, Fe, Ni81Fe19, and Ni) of 0.3, 0.5, 0.8, and 1.3 nm, respectively (with typical standard uncertainties of ±10%). Magnetic metal sandwich diodes, (Au/M/Au/Si) show larger ALs, 0.8 and 2.1 nm, for M=Co and Ni81Fe19, respectively. PtSi interlayers improve the surface roughness but have little effect on the AL while low temperature depositions increase the AL. We presume that the increases in the AL are due to better microstructure, less silicide reaction, or to changes in elastic scattering at interfaces.