Optically Induced Field-Emission Source Based on Aligned Vertical Carbon Nanotube Arrays

Abstract

Due to the high field enhancement factor and photon-absorption efficiency, carbon nanotubes (CNTs) have been widely used in optically induced field-emission as a cathode. Here, we report vertical carbon nanotube arrays (VCNTAs) that performed as high-density electron sources. A combination of high applied electric field and laser illumination made it possible to modulate the emission with laser pulses. When the bias electric field and laser power density increased, the emission process is sensitive to a power law of the laser intensity, which supports the emission mechanism of optically induced field emission followed by over-the-barrier emission. Furthermore, we determine a polarization dependence that exhibits a cosine behavior, which verifies the high possibility of optically induced field emission.

A tunable photo-electric co-excited point electron source: low-intensity excitation emission and structure-modulated spectrum-selection

“…Considering that the repetition frequency of the employed laser is 4 MHz and the pulse-width is approximately 100 ps, the white-light excitation below 10 W cm −2 only corresponds to a peak intensity under 25 kW cm −2 , which is far lower than the transient intensity (∼GW cm −2 ) required to stimulate the electron emission solely relying on an optical field. 21,26 Emission current values larger than 10 nA can be obtained under the peak I laser as low as ∼13 kW cm −2 and E bias of less than 0.47 V μm −1 , indicating that the fabricated W needle nano-cold-cathode has a low-threshold field. Under each fixed I laser , the emission current presents a nonlinear exponential dependence with increased E bias .…”

“…[17][18][19] On the other hand, electrons also have the opportunity to directly tunnel through the barrier to form an optical-field-emission (OFE), which is driven by ultrahigh laser excitation intensities over ∼GW cm −2 . 20,21 Recently, people have been fascinated that under excitation by ultrafast light, ultrafast responsive electronic pulses with an ultrashort pulsewidth and extremely high temporal resolution may be implemented. 14,22,23 However, to achieve this, an excitation with high frequency (ultraviolet band) 14,24,25 or high intensity (>1 GW cm −2 ) 17,26 is usually required, which imposes stringent requirements on the laser output and damage threshold of the cathode material, not conducive to device miniaturization and integration.…”

SnO2Nanofibers Network for Cold Cathode Applications in Vacuum Nanoelectronics

“…The development of high performance field emitters has wide perspectives for applications in the field of vacuum electronics, flat panel displays, electron beam and X-ray sources, and microwave amplifiers. [12][13][14] Carbon nanostructures have surely represented since nineties the prototype of FE devices, either as multiwall or singlewall carbon nanotubes (CNTs), [15][16][17][18][19] buckypapers, [20] amorphous diamonds, [21] due to their favorable properties, including high aspect ratio, low work-function, high conductivity, and high mechanical stability. Successively, an enormous number of metallic or semiconductor nanostructures have been tested as field emitters, from 0D nanoparticles [22,23] to 1D nanowires, [24][25][26] nanopillars, [27] nanorods, [28] from 2D nanosheets including graphene [29][30][31][32] and transition metal dichalcogenides [33][34][35][36][37][38][39][40] to 3D foams, [41] networks, [42] nanoflowers, [43] etc.…”

Investigation of the Effect of Structural Properties of a Vertically Standing CNT Cold Cathode on Electron Beam Brightness and Resolution of Secondary Electron Images

“…Especially, the small radius of curvature of the tip of CNT cold cathodes induces a substantial field enhancement effect and decreases the operating voltage of the field emission devices. It is beneficial for a miniaturized electron emission source to be able to be driven stably up to few micro-amperes of current [ 15 , 16 , 17 , 18 , 19 , 20 ]. Moreover, mature CNT synthesis techniques have achieved uniform large areal arrays and site-selective vertically aligned structures.…”