Results 1 - 10 of 705
Results 1 - 10 of 705. Search took: 0.021 seconds
|Sort by: date | relevance|
[en] We studied the photocurrent characteristics of copper sulfide nanowire devices under bias voltages. Under global illumination by a laser beam on the nanowire devices, the magnitude of the photocurrent was often found to be asymmetric with respect to the bias, and in some cases, even the direction of the photocurrent remained unchanged for a bias in the opposite direction. Such an unusual bias dependence can be explained by the asymmetry of the Schottky contacts near the electrodes and by the bias dependent electric field at the contacts, as was confirmed by using scanning photocurrent microscopy.
[en] The following is a description of some studies the author made on the resonant Schottky detectors in the Tevatron. The author doubts that this document contains any information that wasn't known previously, but hopes that this document will serve as a useful self-contained reference for users of the system
[en] Mass and lifetime measurements of stored exotic nuclei is one of the successful experimental programs at the FRS-ESR facility of GSI, Darmstadt. Two experimental techniques, namely Isochronous and time-resolved Schottky mass spectrometry have been developed. Nuclides in a very broad range of half-lives starting from stable down to only a few ten microseconds can be addressed. Single stored ions can be measured which makes these techniques highly efficient. More than 1100 atomic masses have been measured meanwhile. Half-life measurements are performed with bare and few-electron ions. Decay properties of such highly-charged ions can be dramatically different from the ones known in neutral atoms. Single-particle decay spectroscopy has been developed for investigations of two-body beta decays. A brief description of the experimental methods and recent results will be presented. Future experiments at the present facility and the perspectives with the new NuSTAR/ILIMA project at FAIR will be outlined. (author)
[en] We demonstrated n-type Schottky-barrier metal-oxide-semiconductor field-effect transistors (SBMOSFETs) by using a low-temperature oxide dummy gate process to effectively form a high-k metal-gate structure. First, a MOS capacitor made a 5-nm-thick high-K dielectric with a tungsten electrode was fabricated. The equivalent oxide thickness and the flat-band voltage extracted by using a quantum-mechanical capacitance-voltage analysis were 1.69 nm and –0.15 V, respectively. A 2 μm-gate-length n-type SB-MOSFETs with a source and a drain of erbium silicide showed a high on/off-current ratio of about 105 at a drain voltage of 1 V. The subthreshold swing and the saturation current were 81 mV/dec and 100 μA/μm, respectively.
[en] We examine the specific heat of a self-avoiding polymer on a square lattice with repulsive interactions, which exhibits the Schottky anomaly, a peak in the low-temperature region without a divergence in the thermodynamic limit. The low-temperature tail of the specific heat can be explained by the bending energy imposed due to repulsive next-nearest-neighbor interactions, which play the role of local interactions along the chain. For comparison, the specific heat of a polymer without nonlocal self-exclusion is also considered, wherein only the bending energy is present, which is analytically solvable. The specific heat of the self-avoiding repulsive next-nearest-neighbor polymer is also shown to be robust with respect to the addition of repulsive nearest-neighbor interactions, which act only as nonlocal perturbations causing a slight change in the specific heat in the high-temperature region. We also discuss the relevance of the lattice effect in the context of real polymers.
[en] The Schottky anomaly is a peak in the specific heat at low temperatures without divergence, in contrast to a phase transition which is characterized by a singularity of a physical quantity. A model with the analytic form of a density function, where both the phase transition and the Schottky anomaly appear depending on the limit of the model parameters, is presented. The model allows a unified analytic treatment of the phase transition and the Schottky anomaly
[en] The current transport mechanism in permalloy/n-type Ge Schottky diodes was studied over the temperature range from 200 to 400 K. At temperatures above 250 K, the forward current-voltage (I-V ) characteristics of the diode were ideal and obeyed the thermionic emission theory. Below 250 K, however, the recombination process was found to contribute to current transport. Similarly, in reverse bias, the thermionic emission mechanism appeared to dominate current transport at temperatures above 250 K, and the carrier generation mechanism dominated the reverse current below 250 K. A temperature-driven change in the current conduction mechanism from conduction dominated by low-barrier-height patches to conduction dominated by high-barrier-height regions suggests inhomogeneity in the Schottky barrier height. The barrier height inhomogeneity led to deviations in the Richardson constant from its theoretical value at lower temperatures. The room-temperature low-frequency noise measurements taken at different forward biases for the permalloy/n-type Ge Schottky diodes showed a 1/fγ dependence with a tight variation of γ between 1.20 and 1.31. The current dependence of the noise power spectral density exhibited a 1/f noise behavior, indicating the operation of the permalloy/n-type Ge Schottky diodes in the thermionic emission mode.