Hollow Cathode Produced Electron Beams for Plasma Generation: Cathode Operation in Gas Mixtures

Walton, Scott G.; Leonhardt, D.; Fernsler, R. F.

doi:10.21236/ada459268

Cited by 2 publications

(2 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…3a, depends on both the type of reactive gas used and the operating pressure. The differences between gases is assumed to be related to differences in ion-induced secondary emission [54] and the rich gas-phase kinetics associated with the different reactive gas backgrounds. Importantly, the cathode current increases as function operating pressure, regardless of the gas type.…”

Section: A Plasma Characterization and Processingmentioning

confidence: 99%

Plasma-based chemical functionalization of graphene to control the thermal transport at graphene-metal interfaces

Walton

Foley

Hernández

et al. 2017

Surface and Coatings Technology

View full text Add to dashboard Cite

The unique characteristics of graphene have generated much excitement due to its utility across a variety of applications. One of the principal issues inhibiting the development of graphene technologies pertains to difficulties in engineering high-quality metal contacts on graphene. In this regard, the thermal transport at the metal/graphene interface plays a significant role in the overall performance of devices. Here, we demonstrate the use of electron beam produced plasmas to chemically modify graphene and how these modifications can be used to tune the thermal transport s across metal-graphene interfaces. We show that the operating conditions of the plasma can be adjusted to control the character and quantity of chemical moieties at the interface. Typically, when changes in the surface chemistry favor an increase in adhesion between the graphene and metal, the thermal boundary conductance can be notably improved. Interestingly, the conventional approach of adding a titanium "wetting layer" to improve metal adhesion did not improve the thermal boundary conductance at gold contacts.

show abstract

Section: A Plasma Characterization and Processingmentioning

confidence: 99%

Plasma-based chemical functionalization of graphene to control the thermal transport at graphene-metal interfaces

Walton

Foley

Hernández

et al. 2017

Surface and Coatings Technology

View full text Add to dashboard Cite

show abstract

“…In this configuration both the beam energy and current are thus determined by the applied high voltage and the operating background (both pressure and gas mixture). 28 Although they can be operated continuously, we typically operate these sources in a pulsed mode where a high voltage pulse is applied for 1-4 ms at a duty factor of 10-40%. These sources are quite robust but lack in the fine control over the beam characteristics.…”

Section: Electron Beam Generated Plasma Processing Systemmentioning

confidence: 99%

Electron Beam Generated Plasmas for Ultra Low T_eProcessing

Walton

Boris

Hernández

et al. 2015

ECS J. Solid State Sci. Technol.

View full text Add to dashboard Cite

The Naval Research Laboratory (NRL) has developed a processing system based on an electron beam-generated plasma. Unlike conventional discharges produced by electric fields (DC, RF, microwave, etc.), ionization is driven by a high-energy (∼ few keV) electron beam, an approach that can be attractive to atomic layer processing applications. In particular, high electron densities (10 10 -10 11 cm −3 ) can be produced in electron beam generated plasmas, where the electron temperature remains between 0.3 and 1.0 eV. Accordingly, a large flux of ions can be delivered to substrate surfaces with kinetic energies in the range of 1 to 5 eV. This provides the potential for controllably etching and/or engineering both the surface morphology and chemistry with monolayer precision. This work describes the electron beam driven plasma processing system, with particular attention paid to system characteristics and the ability to control the generation and delivery of ions to the surface and their energies. Electron beam generated plasmas are produced by injecting a highenergy electron beam into a gas background, which will ionize, dissociate, and excite atoms or molecules as it traverses the gas volume. While the basic inelastic processes that lead to species production are the same as those in discharge plasmas, the use of energetic electron beams to drive production results in plasmas that have very different properties than conventional discharges. Some of these properties are attractive for plasma-based atomic layer processing applications where, whether etching, depositing, or chemically modifying materials, fine control over the flux and energy of ions is needed. In the case of atomic layer etching, perhaps the single most important need is to tightly control the kinetic energy of ions incident to the processing surface so as to avoid damage while maintaining a reasonable etch rate. [1][2][3] In this regard, a significant advantage of beam-driven plasmas is the inherently low electron temperature T e , which is typically a fraction of an eV in most gas mixtures of technological interest. Importantly, this is true regardless of the plasma density. Thus, one can produce a large fluence of reactive ion and neutral species where the kinetic energy of the ions is as low as a few eV.The interest in electron beam generated plasmas for materials processing can be traced back at least 4 decades. In the early 1970s Bunshah 4 described an electron beam vapor deposition system that utilizes an electron beam to both vaporize the metal and "activate" the background gas. It was also noted by Dugdale 5 that high-energy electron beam systems developed for welding could be employed for "soft vacuum vapor deposition" in a manner similar to that of Bunshah. In the 1980s, Collins and co-workers at Colorado State University, developed electron beam produced plasmas for plasma enhanced chemical vapor deposition of SiO 2 . 6,7 This system used a sheet-like beam of multi-keV electrons injected parallel to the growth substrate. A similar configurat...

show abstract

Hollow Cathode Produced Electron Beams for Plasma Generation: Cathode Operation in Gas Mixtures

Cited by 2 publications

References 15 publications

Plasma-based chemical functionalization of graphene to control the thermal transport at graphene-metal interfaces

Plasma-based chemical functionalization of graphene to control the thermal transport at graphene-metal interfaces

Electron Beam Generated Plasmas for Ultra Low T_eProcessing

Contact Info

Product

Resources

About

Hollow Cathode Produced Electron Beams for Plasma Generation: Cathode Operation in Gas Mixtures

Cited by 2 publications

References 15 publications

Plasma-based chemical functionalization of graphene to control the thermal transport at graphene-metal interfaces

Plasma-based chemical functionalization of graphene to control the thermal transport at graphene-metal interfaces

Electron Beam Generated Plasmas for Ultra Low TeProcessing

Contact Info

Product

Resources

About

Electron Beam Generated Plasmas for Ultra Low T_eProcessing