Demonstration of low voltage field emission

Low-Bremsstrahlung X-Ray Source Using a Low-Voltage High-Current-Density Nanostructured Field Emission Cathode and a Transmission Anode for Markerless Soft Tissue Imaging

“…Figure 3 shows a set of SEM images that illustrates the process flow to fabricate the field emission cathode chip. The process is similar to those reported in [22]- [28] with a few modifications. The cathodes are fabricated on a 6" n-type silicon wafer (1 -cm resistivity) with a film stack consisting of a 100 nm-thick thermal oxide film, a 100 nm-thick siliconrich silicon nitride film and a 500 nm-thick chemical vapor deposited (CVD) oxide film.…”

“…A chlorine-based anisotropic dry etch further etches the exposed silicon to increase the height of the emitters (Figure 3(b)); this serves the purpose of increasing the thickness of the gate oxide layer so that the device can withstand larger bias voltages without breakdown. In the next step, thermal oxidization is performed to fully sharpen the emitter tips to around 10 nm in diameter (Figure 3(c)); the tip sharpening step is different from [22], [26], [28] in that the oxidation is performed before removing the caps, which protects the top of the emitters from oxidizing because of the silicon nitride film. After the oxidation, the nitride and oxide films are then stripped using diluted hydrofluoric acid and hot phosphoric acid (Figure 3(d)), completing the fabrication of the emitters.…”

“…However, unlike Spindt tips, silicon tips can be operated in the supply-limited regime because of the wide tunability of the electrical conductivity of silicon through doping; operating the emitters in the supply-limited regime could be used to increase and uniformize the current emitted by the FEA [31]- [33]. FEAs reported in the literature have maximum per-emitter current of 0.1-0.5 μA/tip [22], [28]- [30], and average current densities similar to those of CNT forest field emission cathodes (0.2-4 A/cm 2 ) [34]- [36]. In addition, unlike metal field emitters and thermionic emitters, silicon emitters can operate at lower vacuum and are resilient to residual oxygen [37], which makes them more compatible with portable applications.…”

Ultralow-voltage boron-doped diamond field emitter vacuum diode

“…Metal [1]- [4] and Si [5]- [7] FEA's, initialized years ago, have limited applications because of their high turn-on electric field and low, unstable emission current. Therefore, several approaches such as diamond-like carbon coating and advanced emitter structures have been proposed to improve the emission characteristics and stability of the silicon and metal emitters [8]- [10].…”

Gyrotron experiments employing a field emission array cathode

“…First proposed over 25 years ago, thin-film field-emission technology has experienced a resurgence in interest as microfabrication technology has matured [7]. The first functioning micron scale field emission devices were made by Spindt [8] and continuous improvements to this process have been made with corresponding improvements in performance [2].…”