Nottingham Effect in Field and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>T</mml:mi><mml:mo>−</mml:mo><mml:mi>F</mml:mi></mml:math>Emission: Heating and Cooling Domains, and Inversion Temperature

Charbonnier, F. M.; Strayer, R. W.; Swanson, L. W.; Martin, E. E.

doi:10.1103/physrevlett.13.397

Cited by 98 publications

(36 citation statements)

References 11 publications

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“…Early studies by Dyke were greatly expanded by Fursey and co-workers. 10 We understand the two basic energy exchange processes, i.e., the Nottingham effect 11,12 and resistive heating, which cause excessive tip heating and lead to a vacuum arc when the FE current exceeds a predictable level, as is illustrated in Fig. 1.…”

Section: Clean Smooth Single Crystal Field Emitters In An Optimimentioning

confidence: 99%

Arcing and voltage breakdown in vacuum microelectronics microwave devices using field emitter arrays: Causes, possible solutions, and recent progress

Charbonnier

1998

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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There is growing interest in high current field emitter arrays (FEAs) capable of delivering high current density and high conductance electron beams, particularly for microwave applications. Large, high packing density molybdenum and silicon FEAs have been placed in ultrahigh vacuum chambers, carefully conditioned, and tested for maximum performance and have yielded total FEA currents of 20–200 mA and beam current densities of 5–2000 A/cm2 at gate voltages of 80–150 V. However similar Mo and Si FEAs, and GaAs edge arrays, when placed in a prototype 10 GHz klystrode amplifier, have failed at 1–4 mA, even for pulsed operation at a low duty factor. Hence, the current must be increased by 25–50 in order to meet klystrode design objectives. We compare the intrinsic FE stable current limits of various materials: Mo, Si, GaAs, ZrC, and ZrC films on Mo emitters. We conclude that Mo FEAs have a high FE current limit but demand an extremely clean environment, Si or GaAs FEAs are more tolerant of a poorer environment but have a relatively low FE current limit, while ZrC/Mo FEAs have at least as equally high a FE current limit as Mo FEAs but are much more robust and tolerate a much poorer environment. We hypothesize that failures of high density Mo FEAs at relatively low current levels (below 1 μA per tip) in a microwave tube are due to ion bombardment of the FEA creating sharp nanoprotrusions on the sides of the emitters, which emit intense, focused electron beams directed at the gate, leading to a vacuum arc. Binh’s recent study presents strong evidence for the ongoing creation and destruction of nanoprotrusions on Mo FEAs. A ZrC thin film coating protects and passivates the Mo FEA surface, thus minimizing nanoprotrusion formation and allowing more stable operation at higher current levels and/or in more degraded environments. Studies of carbide (ZrC, HfC) film coatings on W, Mo, and Si single tips and on Mo and Si FEAs show that indeed the carbide film reduces the work function and operating voltage (by about 25% and 40%, respectively) and increases stability. Other studies still in progress show that blunt ZrC or ZrC/Mo single tips can operate for reasonable periods (∼1 h) at currents averaging 400 μA in ultrahigh vacuum or 200 μA in 10−5 Torr air. More extensive studies are planned to verify and to quantify the advantages of carbide film coatings for producing lower voltage, higher current, environment tolerant, and long life FEAs for various applications.

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Section: Clean Smooth Single Crystal Field Emitters In An Optimimentioning

confidence: 99%

Arcing and voltage breakdown in vacuum microelectronics microwave devices using field emitter arrays: Causes, possible solutions, and recent progress

Charbonnier

1998

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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“…Nottingham heating [62][63][64] and its impact on arcing and temperature rise in sharpened-and, in particular, microfabricated-structures has generated interest [27,65,66] because of the suspected link between tip heating and failure. In particular, Miskovsky et al, argue that significant temperature rises occur near the apex when the cone angle is small (e.g., 15 ) but further down the shank the temperature drops significantly, a finding supported by the work of Ancona as well as Fursey using 3D numerical approaches and treating heat diffusion.…”

Section: A the Nottingham Effectmentioning

confidence: 99%

Electron emission contributions to dark current and its relation to microscopic field enhancement and heating in accelerator structures

Jensen

Lau

Feldman

et al. 2008

Phys. Rev. ST Accel. Beams

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Analytically tractable models of thermal-field emission, field enhancement, and heating mechanisms (Nottingham and resistive) are developed and combined to make estimates of the fields and temperatures that accompany the development and growth of asperities. The relation of asperity dimensions to dark current is discussed in two experimentally motivated examples. The hypothetical relation of microscopic sources of dark current and heating to breakdown is discussed in the context of Nottingham and resistive heating. The latter are estimated using a general thermal-field methodology. A point-charge model is used to find field enhancement factors. Last, a thermal model is used to estimate the temperature dependence of the resistivity and thermal conductivity. Together, these models suggest that conditions can arise in which the temperature at the apex of an asperity can experience growth and contribute to melting or fracture (or both), and that Nottingham heating generally dominates the resistive heating term.

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“…To obtain stable emission currents, modification of rough surfaces and desorption of adsorbed impurities can be simultaneously achievable from surface migration or melting by the increase in temperature at the tip apex. [9][10][11] The temperature at the tip apex can be controlled by the electric field applied to the tip. [5][6][7][8] There are two heating mechanisms, Nottingham heating and Joule heating, in the field emitter.…”

Section: Introductionmentioning

confidence: 99%

Electrical aging of molybdenum field emitters

Lee¹,

Oh²,

Park³

2003

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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Articles you may be interested inField emission properties of individual zinc oxide nanowire field emitter J. Vac. Sci. Technol. B 26, 983 (2008); 10.1116/1.2919146 High-current-density field emission from multiwalled carbon nanotubes by chemical-vapor deposition with effective aging treatment Emission stability of a field emitter array observed by an emission microscope Argon inclusion in sputtered films and the effect of the gas on molybdenum field emitter arraysAs an approach to improve the stability and reliability of molybdenum field emitters with rough surfaces and impurities at tip apex, electrical aging was studied on the basis of the important tip heating mechanism, Nottingham heating, in dc and pulse mode. The effects of electric field in dc mode were investigated using single tips to avoid the averaging effect commonly arising in arrays. The fluctuations of emission currents were remarkably reduced after the exposure to high electric field ͑ϳ100 MV/cm͒. It was responsible for surface migration and impurity desorption at tip apex achieved under high electric field. Since the continuous exposure to high electric field can bring undesirable effects such as tip failures, electrical aging in pulse mode was also investigated. As the peak voltage of pulse was increased, the fluctuation of emission current was rapidly reduced. From the electrical aging experiments for a 0.7 in. field emission display ͑FED͒, it was proven that the poor uniformity of FED could be considerably improved by electrical aging.

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Nottingham Effect in Field andT−FEmission: Heating and Cooling Domains, and Inversion Temperature

Cited by 98 publications

References 11 publications

Arcing and voltage breakdown in vacuum microelectronics microwave devices using field emitter arrays: Causes, possible solutions, and recent progress

Arcing and voltage breakdown in vacuum microelectronics microwave devices using field emitter arrays: Causes, possible solutions, and recent progress

Electron emission contributions to dark current and its relation to microscopic field enhancement and heating in accelerator structures

Electrical aging of molybdenum field emitters

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