An official website of the United States government
Here’s how you know
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
Fundamental limitations to oxide reliability are analyzed in silicon carbide based devices. A barrier height primarily determined by band offsets between metal/SiC and the dielectric, and the electric field in the dielectric results in tunneling current
We propose two verification methods for measurements of noise parameters of amplifiers, particularly low-noise amplifiers (LNAs). One method is a direct measurement of the parameter Trev, the noise temperature from the amplifier input, and the comparison
A near-ambient, variable-temperature noise standard whose physical temperature can be accurately measured was constructed and then measured with the NIST total-power radiometer to test the accuracy of radiometer measurements in the temperature range of 263
Ty R. McNutt, Allen R. Hefner Jr., Alan Mantooth, J L. Duliere, David W. Berning, Ranbir Singh
Dynamic electrothermal circuit simulator models are developed for silicon carbide power diodes. The models accurately describe the temperature dependence of on-state characteristics and reverse-recovery switching waveforms. The models are verified for the
Anna Clark, Anthony Williams, Steve Ruggiero, Marcel L. van den Berg, Joel N. Ullom
We demonstrate a thin-film, solid-state refrigerator based on the removal of hot electrons from a metal by quantum-mechanical tunneling. We have halved the electronic temperature in a macroscopic film from 260 mK to near 130 mK. Both the cooling power and
Steve Ruggiero, Anthony Williams, W. H. Rippard, A. Clarke, Steven Deiker, Leila R. Vale, Joel N. Ullom
We discuss results on the superconducting and electron-transport properties of Mn doped Al produced by sputter deposition. The critical temperature of Al has been systematically reduced to below 50 mK by doping with 1000-3000 ppm Mn. Values of the α
Matthew Shaw, Giovanni Di Giuseppe, A. Sergeinko, Bahaa E. A. Saleh, Malvin C. Teich, Aaron J. Miller, Sae Woo Nam
The seminal experiment carried out by Hong, Ou, and Mandel some fifteen years ago is one of the most important in the annals of quantum optics. This experiment demonstrated that two indistinguishable photons incident on a simple beam splitter interfere in
Xudong Huang, Pepa Elton, Jih-Sheng Lai, Allen R. Hefner Jr., David W. Berning, Shaotang Chen, Thomas Nehl
In this paper , a permanent magnet ac motor drive is tested extensively, and the prominent frequencies are identified for their relationship with the noise sources and their propagation paths. Switching characteristics of the power MOSFETs are evaluated
David W. Berning, John V. Reichl, Allen R. Hefner Jr., Mora Hernandez, Colleen E. Hood, Jih-Sheng Lai
A measurement system operates a multi-chip insulated gate bipolar transistor (IGBT) that is part of an integrated power electronic module (IPEM) in a high-pulsed-power linear mode for validation of dynamic thermal models. It is found that the gate-cathode
Allen R. Hefner Jr., Ty R. McNutt, David W. Berning, Ranbir Singh, Adwoa Akuffo
Abstract. The role of excess carrier lifetime reduction in the mechanism for on-state voltage (Vf) degradation of high voltage 4H-SiC PiN diodes is investigated. A method is developed to electrically monitor the emitter, base, and end region excess carrier
Nhan Van Nguyen, Jin-Ping Han, Yong Jai Cho, Wenjuan Zhu, Zhijiong Luo, T P. Ma
In this report, we use vacuum ultraviolet spectroscopic ellipsometry (VUV-SE) to determine the optical as well as structural properties of high-k metal oxides, in particular, of Hafnium Aluminates and Titanium Aluminates. Two sets of samples consisting of
Carl D. Reintsema, Joern Beyer, Sae Woo Nam, Steven Deiker, Gene C. Hilton, Kent D. Irwin, Joel N. Ullom, Leila R. Vale, Michael MacIntosh
We discuss the implementation of a time-division SQUID multiplexing system for the instrumentation of large-format transition-edge sensors (TES) arrays. We cover design and integration issues concerning cryogenic SQUID multiplexers and amplifiers, signal
We report on the development of a microwave power limiter based on high temperature superconductor technology. The power limiter takes the form of a 50 Ω coplanar waveguide transmission line that can be reversibly driven into the normal state as microwave
We demonstrate how nonlinear effects in high temperature superconducting thin films can be quantified based on a current-dependent penetration depth λ(J). Using an assumed form for λ(J), we calculate the expected third-order harmonic signals generated by
Ty R. McNutt, Allen R. Hefner Jr., Alan Mantooth, David W. Berning, Sei-Hyung Ryu
A compact circuit simulator model is used to describe the performance of a 2000-V, 5-A 4-H Silicon Carbide (SiC) power DiMOSFET and to perform a detailed comparison with the performance of a widely used 400-V, 5-A Silicon (Si) power MOSFET. The model's
We have designed, fabricated, and tested a microwave power limiter based on high temperature superconductor thin film technology. The signal limiter takes the form of a 50 Ohm} coplanar waveguide transmission line that is reversibly driven from the low
The origin of the detrimental nonlinear response in the high Tc superconductor (HTS) microwave devices is currently not well understood. In order to help elucidate the origin of these nonlinear effects, we have performed phase-sensitive measurements of the
Precise measurements of the surface resistance of high temperature superconducting thin films using transmission mode dielectric resonators requires accurate knowledge of the unloaded Q factor. So far, the most accurate method of unloaded Q factor
James Booth, Sang Y. Lee, Kenneth Leong, J. H. Lee, J. Lim, H. N. Lee, S. H. Moon, B. Oh
We have measured the temperature dependence of the microwave surface impedance and the nonlinear response of high-quality MgB 2 films on c-cut sapphire at temperatures below 40 K. MgB 2 films with surface resistance (Rs) as low as 0.09 mOhm} at 8 K and 19
Uwe Arz, Dylan F. Williams, Dave K. Walker, Luoh A, Hartmut Grabinski, Andreas Weisshaary
New broadband closed-form expressions for the frequencydependent impedance parameters of asymmetric coupled coplanar interconnects on a conductive silicon substrate are presented. The closed-form expressions are based on a complex image approach that
David B. Newell, Edwin R. Williams, John A. Kramar, Jon R. Pratt, Douglas T. Smith
The National Institute of Standards and Technology (NIST) has launched a five-year Micro-force Realization and Measurement project focusing on the development of an instrument and laboratory capable of realizing and measuring the SI unit of force below
This is a summary of recent efforts conducted under the auspices of the American National Standards Institute (ANSI) Accredited Standards Committee C63, Sub-committee 1, working group 1-13.2. The main purpose of this group is to assess the applicability of
Muhammad Afridi, John S. Suehle, Mona E. Zaghloul, David W. Berning, Allen R. Hefner Jr., Richard E. Cavicchi, Stephen Semancik, C B. Montgomery, C J. Taylor
A monolithic CMOS microhotplate-based conductance type gas sensor system is described. A bulk micromachining technique is used to create suspended microhotplate structures. The thermal properties of the microhotplates include a one-millisecond thermal time
Ranbir Singh, Kenneth G. Irvine, D C. Capell, James Richmond, David W. Berning, Allen R. Hefner Jr., John W. Palmour
This paper reports the design, fabrication, and high temperature characteristics of 1 mm 2, 4 mm 2, and 9 mm 2 4H-SiC rectifiers with 6 kV, 5 kV, and 10 kV blocking voltage respectively. These results were obtained from two lots in an effort to increase