Electron Emission from Metals Excited with a CW CO2 Laser

1974 ◽  
Vol 52 (6) ◽  
pp. 475-481
Author(s):  
W. W. Duley
Keyword(s):  
Time Dependence ◽  
Electron Emission ◽  
Thermionic Emission ◽  
Exoelectron Emission ◽  
Electron Current ◽  
Surface Sites ◽  
Complex Dependence ◽  
Cw Co2 Laser ◽  
Ion Emission

The time dependence of electron and ion emission from roughened metals on excitation with a CW CO2 laser has been studied. The emission currents are made up of pulses with durations of several ms. A complex dependence of both ion and electron current on time is observed on time scales ranging from ms to days. An interpretation of these effects based on thermionic emission from localized surface sites is given, and the possible role of exoelectron emission is discussed. Some possible applications of these effects are examined.

Image Enhancement in the Emission Electron Microscope

1973 ◽  
Vol 31 ◽  
pp. 90-91
Author(s):  
R. C. McCune
Keyword(s):  
Spatial Distribution ◽  
Image Enhancement ◽  
Electron Emission ◽  
Low Temperatures ◽  
Thermionic Emission ◽  
Exoelectron Emission ◽  
Channel Electron Multiplier ◽  
Electron Multiplier ◽  
Unique Approach ◽  
Electron Emissions

A thermionic emission microscope designed by Eichen, and described in the literature, has been modified to allow the use of the Bendix Chevron type Channel Electron Multiplier Array (CEMA) for purposes of image enhancement. The CEMA provides a means of obtaining a spatial distribution of the electron emission occurring on the surface of the specimen, and as such provides a unique approach to problems of obtaining both thermionic emission images at relatively low temperatures and images produced by the phenomenon of exoelectron emission.In order to observe single electron emissions on a phosphor screen, it is essential that an electron multiplier be operated at gains approaching 107.

scholarly journals Carbon Nanotube Electron Sources: From Electron Beams to Energy Conversion and Optophononics

2014 ◽  
Vol 2014 ◽  
pp. 1-23 ◽  
Author(s):  
Alireza Nojeh
Keyword(s):  
Carbon Nanotubes ◽  
Field Emission ◽  
Electron Emission ◽  
Electron Beams ◽  
Thermionic Emission ◽  
Secondary Emission ◽  
Electron Sources ◽  
Field Emitters ◽  
Electron Microscopes ◽  
Electron Emitters

Carbon nanotubes have a host of properties that make them excellent candidates for electron emitters. A significant amount of research has been conducted on nanotube-based field-emitters over the past two decades, and they have been investigated for devices ranging from flat-panel displays to vacuum tubes and electron microscopes. Other electron emission mechanisms from carbon nanotubes, such as photoemission, secondary emission, and thermionic emission, have also been studied, although to a lesser degree than field-emission. This paper presents an overview of the topic, with emphasis on these less-explored mechanisms, although field-emission is also discussed. We will see that not only is electron emission from nanotubes promising for electron-source applications, but also its study could reveal unusual phenomena and open the door to new devices that are not directly related to electron beams.

scholarly journals The Role of Silicon Heterojunction and TCO Barriers on the Operation of Silicon Heterojunction Solar Cells: Comparison between Theory and Experiment

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Yaser Abdulraheem ◽  
Moustafa Ghannam ◽  
Hariharsudan Sivaramakrishnan Radhakrishnan ◽  
Ivan Gordon
Keyword(s):  
Solar Cells ◽  
Large Scale ◽  
Surface Passivation ◽  
Series Resistance ◽  
Crystalline Silicon ◽  
Thermionic Emission ◽  
Analytical Description ◽  
Theoretical Explanation ◽  
The Impact

Photovoltaic devices based on amorphous silicon/crystalline silicon (a-Si:H/c-Si) heterojunction interfaces hold the highest efficiency as of date in the class of silicon-based devices with efficiencies exceeding 26% and are regarded as a promising technology for large-scale terrestrial PV applications. The detailed understanding behind the operation of this type of device is crucial to improving and optimizing its performance. SHJ solar cells have primarily two main interfaces that play a major role in their operation: the transparent conductive oxide (TCO)/a-Si:H interface and the a-Si:H/c-Si heterojunction interface. In the work presented here, a detailed analytical description is provided for the impact of both interfaces on the performance of such devices and especially on the device fill factor ( FF ). It has been found that the TCO work function can dramatically impact the FF by introducing a series resistance element in addition to limiting the forward biased current under illumination causing the well-known S-shape characteristic in the I-V curve of such devices. On the other hand, it is shown that the thermionic emission barrier at the heterojunction interface can play a major role in introducing an added series resistance factor due to the intrinsic a-Si:H buffer layer that is usually introduced to improve surface passivation. Theoretical explanation on the role of both interfaces on device operation based on 1D device simulation is experimentally verified. The I-V characteristics of fabricated devices were compared to the curves produced by simulation, and the observed degradation in the FF of fabricated devices was explained in light of analytical findings from simulation.

Evaluation of On-State Resistance and Boron-Related Levels in n-Type 4H-SiC

2005 ◽  
Vol 483-485 ◽  
pp. 425-428 ◽  
Author(s):  
R.R Ciechonski ◽  
Samuele Porro ◽  
Mikael Syväjärvi ◽  
Rositza Yakimova
Keyword(s):  
Minority Carrier ◽  
Deep Level ◽  
Schottky Diodes ◽  
Depth Profiling ◽  
Thermionic Emission ◽  
Barrier Heights ◽  
Transient Spectroscopy ◽  
State Resistance ◽  
Thick Layers

Specific on-resistance Ron estimated from current density-voltage characteristics of Schottky diodes on thick layers exhibits variations from tens of mW.cm2 to tens of W.cm2 for different doping levels. In order to understand the occurrence of high on-state resistance, Schottky barrier heights were first estimated for both forward and reverse bias with the application of thermionic emission theory and were in agreement with a literature reported values. Decrease in mobility with the temperature was observed and its dependencies of T–1.3 and T–2.0 for moderately doped and low doped samples respectively were estimated. From deep level measurements by Minority Carrier Transient Spectroscopy, an influence of shallow boron related levels and D-center on dependence of on-state resistance was observed, being more pronounced in low doped samples. Similar tendency was observed in depth profiling of Ron. This suggests a major role of boron in a compensation mechanism thus resulting in high Ron.

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