Current crowding effects in a CdS/LaS cold cathode

Mumford, Philip; Cahay, M.

doi:10.1063/1.365492

Cited by 13 publications

(15 citation statements)

References 4 publications

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“…With enough forward bias on the emitter fingers, electrons emitted from the InP substrate tunnel through the CdS layer and are emitted into vacuum as a result of NEA at the CdS/LaS interface. However, there can be partial trapping of electrons by the LaS semimetallic thin film, which can lead to a lateral current flow and current crowding 11,12 and self-heating effects 13 in the cathode.…”

Section: Our Work Was Motivated By the Original Proposal By Walter Frmentioning

confidence: 99%

Review Article: Rare-earth monosulfides as durable and efficient cold cathodes

Cahay¹,

Fairchild²,

Grazulis³

et al. 2011

Journal of Vacuum Science & Technology B, Nanotechnology an

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In their rocksalt structure, rare-earth monosulfides offer a more stable alternative to alkali metals to attain low or negative electron affinity when deposited on various III-V and II-2 VI semiconductor surfaces. In this article, we first describe the successful deposition of Lanthanum Monosulfide (LaS) via pulsed laser deposition on Si and MgO substrates and alumina templates. These thin films have been characterized by X-ray diffraction, atomic force microscopy, high resolution transmission electron microscopy, ellipsometry, Raman spectroscopy, ultraviolet photoelectron spectroscopy and Kelvin probe measurements. For both LaS/Si and LaS/MgO thin films, the effective work function of the submicron thick thin films was determined to be about 1 eV from field emission measurements using the Scanning Anode Field Emission Microscopy technique. The physical reasons for these highly desirable low work function properties were explained using a patchwork field emission model of the emitting surface. In this model, nanocrystals of low work function materials having a <100> orientation perpendicular to the surface and outcropping it are surrounded by a matrix of amorphous materials with higher work function. To date, LaS thin films have been used successfully as cold cathode emitters with measured emitted current densities as high as 50 A/cm 2 . Finally, we describe the successful growth of LaS thin films on InP substrates and, more recently, the production of LaS nanoballs and nanoclusters using Pulsed Laser Ablation.3

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Section: Our Work Was Motivated By the Original Proposal By Walter Frmentioning

confidence: 99%

Review Article: Rare-earth monosulfides as durable and efficient cold cathodes

Cahay¹,

Fairchild²,

Grazulis³

et al. 2011

Journal of Vacuum Science & Technology B, Nanotechnology an

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“…16,17 Of particular interest is the fact that the room temperature WF of these chalcogenides, when extrapolated from high-temperature measurements, 18 are quite low ͑between 1 and 1.4 eV͒. I, the Fano factor is expected to be substantially below unity for metallic cathodes with WF much smaller than the values characterizing most common metals which are within the 4 -5 eV range.…”

Section: Numerical Examplesmentioning

confidence: 99%

Shot noise power spectrum of planar field emitters

Rangaswamy¹,

Cahay²,

Jensen³

2005

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

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A quantum-mechanical wave impedance approach is used to calculate the shot noise power spectrum of the emission current from planar metallic cathodes. The formalism takes into account the effects of the image force potential in front of the cathode. For metals with low work function, the Fano factor which characterizes the reduction of the shot noise power S I below the Schottky result 2 q I A ͑where q is the magnitude of the charge of the electron and I A is the time average of the anode current͒ is calculated as a function of the applied external electric field. Simple analytical expressions for the Fano factor are derived for the cathode operated in the thermionic ͑Richardson͒ and tunneling ͑Fowler-Nordheim͒ regimes. The value of the Fano factor is found to be reduced substantially below the value calculated when the effects of the image charge potential are neglected.

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“…2,3 The main elements in the design and functioning of the emitter are ͑1͒ a wide band gap semiconductor ͑undoped CdS͒ sandwiched between a metallic contact that supplies electrons into the CdS conduction band at a sufficient rate and ͑2͒ a thin semimetallic film that facilitates coherent transport ͑tunneling͒ of electrons from the semiconductor conduction band into vacuum.…”

Section: Importance Of Space-charge Effectsmentioning

confidence: 99%