Direct Refrigeration by Electron Field Emission From Diamond Microtips

2000 ◽  
Author(s):  
T. S. Fisher ◽  
D. G. Walker
Keyword(s):  
Energy Conversion ◽  
Field Emission ◽  
Current Density ◽  
High Capacity ◽  
Wide Band ◽  
Electrical Current ◽  
Emission Current Density ◽  
High Energy ◽  
Electron Field Emission ◽  
Electron Field

Abstract This paper describes a concept for creating high-capacity, direct electrical-to-thermal energy conversion for compact cooling based on electron field emission. Electron field emission involves the transport of electrons that tunnel through a potential barrier. The thermodynamics of field emission have remained relatively unexplored. However, emission from wide-band-gap semiconductors, such as diamond, is known to produce an energy filtering effects such that high-energy electrons possess higher probabilities of emission. Lower energy electrons replace the emitted electrons, and thus, this process can produce a refrigeration effect. The refrigeration capacity is proportional to the emission current density, which is very high for diamond emitters. This high electrical current density implies that high thermal current densities are possible. The present work provides a thermodynamic analysis and energy conversion predictions based on experimental current-voltage data from diamond tip emitters. Energy fluxes in excess of 100 W/cm2 are predicted by the theory for room-temperature operation.

Electron Field Emission from Nano-Diamond Films

2001 ◽  
Vol 704 ◽  
Author(s):  
S.G. Wang ◽  
Q. Zhang ◽  
S.F. Yoon ◽  
J. Ahn ◽  
Q. Wang ◽  
...  
Keyword(s):  
Grain Size ◽  
Electric Field ◽  
Field Emission ◽  
Current Density ◽  
Diamond Films ◽  
Emission Current Density ◽  
Hydrogen Gas ◽  
Emission Current ◽  
Electron Field Emission ◽  
Electron Field

AbstractIn this paper, the field emission properties of nano-diamond films were investigated by measuring the curves of emission current density (J) versus applied electric field (E). The nano-diamond films were prepared on n-type (100) silicon substrate by microwave plasma enhanced chemical vapor deposition (MPECVD) technique using a gas mixture of nitrogen-methane-hydrogen. Field emission results show that, with increasing hydrogen gas flow ratio of [H2]/[N2+CH4+H2] from 0 to 10 %, diamond grain size increases from 5 to 60 nm, threshold electric field for electron field emission increases from 1.2 to 5.75 V/μm, and emission current density decreases from 820 to 560 μA/cm2, demonstrating that small grain size nano-diamond films are promising as a cathode material for low-field electron emitters.

Thermal and Electrical Energy Transport and Conversion in Nanoscale Electron Field Emission Processes

2002 ◽  
Vol 124 (5) ◽  
pp. 954-962 ◽  
Author(s):  
T. S. Fisher ◽  
D. G. Walker
Keyword(s):  
Energy Conversion ◽  
Field Emission ◽  
Energy Transport ◽  
Exchange Process ◽  
Electrical Energy ◽  
Electron Field Emission ◽  
Operational Parameters ◽  
Transfer Rates ◽  
Conversion Rates ◽  
Electron Field

This paper considers the theory of electron field emission from nanoscale emitters with particular focus on thermal and electrical energy transport. The foundational theory of field emission is explored, and a model is presented that accounts explicitly for the energy band curvature produced by nanoscale tip emitters. The results indicate that the inclusion of band curvature strongly influences the energetic distribution of electrons for emitter radii less than 50 nm. The energy exchange process between emitted and replacement electrons is shown to allow high local energy transfer rates that can be exploited in direct thermal-to-electrical energy conversion processes. The dependence of energy conversion rates on material and operational parameters is demonstrated. Throughout the paper, opportunities for further research involving nanoscale heat transfer, materials development, and modeling are highlighted.

Electron field emission from wide band-gap semiconductors (GaN)

2009 ◽  
Author(s):  
V. Litovchenko ◽  
A. Grygoriev ◽  
A. Evtukh ◽  
O. Yilmazoglu ◽  
H. Hartnagel ◽  
...  
Keyword(s):  
Band Gap ◽  
Field Emission ◽  
Wide Band ◽  
Electron Field Emission ◽  
Wide Band Gap ◽  
Electron Field ◽  
Wide Band Gap Semiconductors

Experimental Characterization of Anode Heating Due to Electron Emission From an Individual Carbon Nanotube

2004 ◽  
Author(s):  
T. L. Westover ◽  
T. S. Fisher ◽  
V. Chopra ◽  
F. E. Pfefferkorn
Keyword(s):  
Carbon Nanotube ◽  
Field Emission ◽  
Infrared Camera ◽  
Bias Field ◽  
High Energy ◽  
Electrical Circuit ◽  
Anode Surface ◽  
Electron Field Emission ◽  
Repeated Testing ◽  
Electron Field

Electron field emission is the process by which electrons tunnel from a cathode to an anode, usually through vacuum, by the application of a large voltage bias. Field-emission devices find applications in flat panel displays, electrical circuit breakers, and power diodes. A significant amount of heat can be transferred to the anode from high-energy electrons as they impact the anode surface. This study investigates the heating of a thin, disc-shaped steel anode by field-emitted electrons from a single carbon nanotube. Experiments have demonstrated a temperature rise of more than 11.0 C at the anode center at an energy deposition rate of 16 mW. A finite-difference model is employed to predict the steady-state anode temperature profile resulting from electron field emission, and this profile is compared to that obtained from measurements taken with an infrared camera. The comparison yields information regarding the diameter of the electron beam as it strikes the anode. The paper also discusses significant experimental challenges, which include attaching individual nanotubes on a tungsten needle to withstand the applied electric field and obtaining consistent results during repeated testing.

Ain Thin Films Prepared by Reactive Ion Beam Coating

1999 ◽  
Vol 585 ◽  
Author(s):  
L. L. Cheng ◽  
Y H. Yu ◽  
B. Sundaravel ◽  
E. Z. Luo ◽  
S. Lin ◽  
...  
Keyword(s):  
Thin Films ◽  
Field Emission ◽  
Ion Beam ◽  
Wide Band ◽  
Electron Field Emission ◽  
Emission Properties ◽  
Field Emission Properties ◽  
Preparation Conditions ◽  
Electron Field ◽  
Electron Field Emission Properties

AbstractAluminum Nitride (AIN) is a promising material for a variety of technological applications because it has many exceptional properties, such as wide band gap (WBG) and negative electron affinity (NEA). AIN thin films were prepared by Reactive Ion Beam Coating. The properties of the AIN thin films may be a function of one of the preparation conditions: the beam energy. We used the non-Rutherford backscattering (non-RBS) and Auger Electron Spectroscopy (AES) results to analyze the composition of the AIN thin films. Atomic Force Microscopy (AFM) was applied to study the morphology of films. On the other hand, electron field emission properties were also studied to find the relationship between the compositional, morphological and electron field emission properties of the AIN thin films.

Electron Field Emission Characteristics of Silicon Nanodots Formed by the LPCVD Technique

2011 ◽  
Vol 49 (4) ◽  
pp. 342-347
Author(s):  
Kyoungwan Park ◽  
Seungman An ◽  
Taekyung Yim ◽  
Kyungsu Lee ◽  
Jeongho Kim ◽  
...  
Keyword(s):  
Field Emission ◽  
Emission Characteristics ◽  
Electron Field Emission ◽  
Electron Field
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