Operation of nanocrystalline silicon ballistic emitter in low vacuum and atmospheric pressures

Abstract

To make the specific features of nanocrystalline silicon (nc-Si) cold cathode clear, its emission characteristics are investigated in low vacuum and atmospheric pressure. The experimental nc-Si diode is composed of a thin Au film, a nanocrystallized polysilicon layer, an n-type silicon wafer, and a back contact. It is shown that the ballistic electron emission mode of the nc-Si device is kept alive until the vacuum pressure is increased to about 10Pa, and that a significant current signal is detected at the collector even in air. The current observed in air can be interpreted as a result of energetic electron attachment into oxygen molecules in proximity to the front surface. The effectiveness of this emitter for the use in air is applied to surface charging of an insulating polymer. The experimental results demonstrate that the surface of a polymer film located in air at a distance of 1mm from the device surface is quickly charged up to a certain negative potential determined from the collector voltage. The surface-emitting nc-Si ballistic emitter is useful not only in vacuum, but also in air and gas ambient for various applications.

Silicon Nanocrystals in Porous Silicon and Applications

“…PSi acts as a drift layer producing ballistic electrons (injected into the layer from the substrate) via multiple-tunneling cascade under an external electric field applied between the substrate and a top metal electrode. As a result, ballistic electron of several electron volts in energy (Figure 14.3a) can be emitted from the top metal electrode into a vacuum [123,124], a gas (up to atmospheric pressures) [125,126], or directly into a material deposited onto PSi [127][128][129]. When operated into vacuum, the emission efficiency (emission current divided by current flowing through the diode) has reached 12% [123].…”

“…It is less sensible to ambient pressure [125,126], exhibits a smaller [127]. Reproduced with permission from Ref.…”

“…14.4.1.5.3 Ballistic Electron Emission in Gas and Liquids Electron emission in air and different gases at various pressures (up to atmospheric pressures) has been reported [125,126]. In air, about 1 mA/cm 2 was detected at the collector electrode located at a distance of 1 mm from the emitter surface.…”

“…The operation stability in air has been improved combining several surface treatments: high-pressure water vapor annealing, forming gas (N 2 þ H 2 ) annealing, and chemical modification [126]. An application is surface charging of an insulating polymer [125]. The polymer can be quickly charged up to a certain negative potential determined by the collector voltage.…”

Thin Cu Film Deposition by Operation of Nanosilicon Ballistic Electron Emitter in Solution

“…The mean energy of output electrons reaches 5-7 eV at applied voltages of 15-20 V. This nc-Si ballistic planar emitter has several advantages: ͑i͒ highly energetic and directional emitted electrons; 7 ͑ii͒ compatibility with silicon planar processing at low temperatures; ͑iii͒ relatively low operating voltage; ͑iv͒ insensitivity to vacuum pressure; 8 ͑v͒ quick dynamic response; 9 and ͑vi͒ availability for emitter array fabrication on large-area glass substrate. 10 The nc-Si ballistic emitter has versatile technological potentials in various media such as flat panel display 11 and parallel electronbeam lithography 12 in vacuum, negative ion source in air applicable to the latent image formation, 8 and vacuum-UV light emission by internal excitation of xenon molecules. 13 Another important opportunity is that the nc-Si ballistic emitter operates as an active electrode that supplies strongly reducing electrons into pure water 14 and aqueous solutions.…”