Comments on nonlinearity,response time and polarity reversal in a thermal field emission metal whisker diode

In a series of recent experiments, research groups have made absolute frequency measurements with laser beams in the infrared region (μm) using a metal-metal point contact diode for the generation, frequency mixing and detection. At present there are two models which attempt to explain the rectification mechanism of the diode: 1) Tunneling of electrons through an intermediate oxide film from whisker to the metal base, i.e., configuration is considered to be a metal-oxide-metal (MOM) tunneling junction. 2) Rectification and nonlinear processes are the result of a thermal enchanced field emission. Such emission is a consequence of the immersion of the whisker in the laser radiation which results in conduction induced thermionic emission and/or generation of an electric field at the tip necessary for electron tunneling by field emission. The purpose of this comment is: a) to discuss qualitatively the basic difference between MOM and TFE theories as regards the origin of the nonlinearity and rectification properties of the metal point contact junction; b) to review the analyses describing the ultimate frequency response of the device; and 3) to provide a possible explanation for polarity reversal consistent with the TFE mechanism describing the operation of the whisker diode. This research was supported in part by the NATO Research Grants Program, Scientific Affairs, Brussels, Belgium, and under the auspices of the joint projects ESIS (electronic structure in solids) and IRIS (Institute for Research in Interface Sciences) of the Belgian Ministry for Science Policy     

Thermal field emission as a mechanism for infrared laser light detection in metal whisker diode

The non-linear current-voltage characteristic of thermally enhanced field emission is proposed to explain the operation of a metal-metal point contact diode used for laser harmonic frequency generation and frequency mixing in the infrared region. This mechanism can explain several experimental observations which appear inconsistent with the previous analysis based on a planar metal-oxide-metal tunneling geometry.     

Thermal and field emission effects of laser radiation on metal whisker diodes: Application to infrared detection devices

In a series of recent experiments, research groups have made absolute frequency measurements with laser beams in the infrared region of the spectrum (λ ? 10 μm) using a metal point contact diode for generation, frequency mixing and detection. It has been postulated that the mechanism for the nonlinear current-voltage characteristic of the diode is tunnelling of electrons through an intermediate oxide film from the whisker into the metal base, i.e., the configuration is considered to be a metal-oxide-metal (MOM) tunnelling junction. Several features of the diode's operation create considerable doubt concerning the applicability of the MOM tunnelling mechanism. Analysis of the available experimental data led us to postulate an alternate solid state mechanism, namely a thermally enhanced field emission process. Such emission would be a consequence of the immersion of the whisker tip in the laser radiation resulting in (1) conduction heating which induces thermionic emission and (2) generation of an electric field at the tip necessary for electron tunnelling by field emission. In this paper we calculate rigorously the power absorbed in the metal whisker from the incident radiation. From the power absorbed, the heat conduction equation is solved for model geometries to obtain the laser induced temperature distribution at the whisker surface. Estimates of the electric field are obtained and combined with temperature calculations to obtain the nonlinear I–V characteristics of the thermally enhanced field emission model. Finally some simple experiments are proposed to test the thermal field emission hypothesis as a possible mechanism to explain the nonlinear characteristics of the metal whisker point contact diode.     

非平行板电容器电场和电容的另一种计算

通过求解电势的拉普拉斯方程,得到非平行板电容器两极板间的电势分布,从而求出其电场和电容,结果与用其他方法所得结果完全相同．     

Transients in a semiconductor diode having an electric field in the base

The transients in a diode with a finite inhomogeneous base (one with a dope gradient) are discussed, no condition being imposed on the recombination rate at the ohmic contact; it is assumed that the electric field is of constant strength along the base. It is found that the transients are shorter than those in a diode with a homogeneous base.     

Measurement and study of the embedding impedance presented by the whisker antenna of a schottky diode corner cube mixer

A 250× scale model of a Schottky diode corner cube mixer designed for operation in the terahertz region has been built and tested. It has been successfully used to measure the embedding impedance presented to the diode at the whisker tip and also determine the impedance of the whisker antenna itself. The results have been input into a computer analysis to determine as to how the performance may be improved. With regards to improving the physical ruggedness of such mixers, a simple equivalent whisker structure has been determined and a new technique that may be used to fabricate a space qualifiable corner cube mixer intended for terahertz operation is disclosed.     

The theory of a rotating plasma in crossed electric and magnetic fields

The paper presents an analysis of the behaviour of a weakly ionized gas confined by cylindrical electrodes and dielectric fronts. An ionized gas is put into a rotational movement by transverse electric and longitudinal magnetic fields. Quantities describing a plasma in the stationary state have been obtained by solving a system of macroscopic equations. Some of them are compared with experimental data.I would like to express my thanks to ing. L. ípek CSc for providing me with the experimental data obtained with the device BXE1. My thanks are also due to ing. V. Kopecký CSc for valuable comments.     

Plasma in a metal layer exposed to an RF electric field

The response of electrons in a metal layer (sheet) to a variable electric field normal to the surface is studied under resonance conditions, i.e., when the frequency of the field is close to the plasma oscillation frequency. The electromagnetic field energy absorbed in the sheet is calculated.     

Towards a theory of the field emission of electrons

Application of a generalized WKB method to the investigation of the field emission of electrons from conductors and semiconductors is considered. Formulas are obtained for estimating the coefficients of transmission of electrons through a potential barrier created by an external electric field and the image force.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii Fizika, No. 11, pp. 7–13, November, 1972.     

The role of built-in electric fields in the InGaN/GaN quantum-well emission

By analyzing the evolution of time-resolved photoluminescence spectra, it is detected experimentally for the first time that there is a correlated effect of built-in electric fields and of long-lived localized states on the formation of emission in quantum wells based on nitrides of Group III elements. It is shown that light-emitting diode structures can be classified for commercial applications by studying time-resolved photoluminescence spectra.     

The temperature dependence of the electric field gradient in ruthenium metal

The electric field gradient in ruthenium metal was studied between 15 K and 863 K. In contradiction to a recently proposed theory [1] the EFG was found to decrease with increasing temperature.     

The electric field gradient for Gd in gadolinium metal

We have examined the temperture dependence of the efg for GdGd above the Curie point. Using anI =10⁺ isomer in¹⁴⁴Gd as a probe nucleus, we find a weakT ^3/2 dependence withB=(1.5±0.4) 10^–5 K^–3/2. The absolute value of the efg at 332 K was measured by Coulomb excitation of 2⁺ states in^{156, 158, 160}Gd, yielding |eq(332 K)|=(3.43±0.14) 10¹⁷ V/cm². A possible small deviation from theT ^3/2 temperature dependence of the efg for ferromagnetic Gd is discussed.     

Terahertz emission from square wells in a longitudinal electric field

Terahertz emission accompanying heating of two-dimensional electrons by a strong electric field applied along size-quantized GaAs/AlGaAs layers is observed and investigated. The emission is due to indirect optical transitions of hot electrons in the bottom size-quantization band. The experimentally obtained emission spectra are compared with the spectra calculated taking into account scattering of electrons by optical phonons, impurities, and interfacial roughness and electron-electron scattering. Satisfactory agreement is obtained. The temperature of the hot electrons is determined from a comparison of the spectra. Pis’ma Zh. éksp. Teor. Fiz. 67, No. 7, 507–511 (10 April 1998)     

The influence of electric of H- near field on the photodetachment a metal surface

The influence of electric field on the photodetachment of H- near a metal surface is investigated based on the closed-orbit theory. It is found that the photodetachment of H- near a metal surface is not only related to the electric field strength but also to the electric field direction. If the electric field is along the ＋z axis, it can strengthen the oscillation in the photodetachment cross section. However, if the electric field is along the -z axis, since the direction of electric field force is opposite to that of static-image force caused by the metal surface, the situation becomes much more complicated. When the electric field is very weak, its influence can be neglected. The photodetachment cross section is nearly the same as that when a single metal surface exists. When the electric field strength is strong enough, the electric field force is able to counteract the metallic attraction, therefore no closed orbit is formed. If the electric field continues to increase until its influence becomes dominant, the photodetachment cross section approaches the case of the photodetachment of H^- in an electric field. Our results may be useful for guiding future experimental studies on the photodetachment of negative ions near surfaces.