Nanodiamond Lateral Field Research Articles

Fabrication and implementation of nanodiamond lateral field emission diode for logic OR function

This article reports successful fabrication and characterization of vacuum microelectronic OR gate logic using nanodiamond lateral diode structures. Two identical sets of four nanodiamond lateral diodes with different numbers of emitters, viz., 125, 325, 2340 and 9360, and with equal anode–cathode spacing of ~3.5-μm were fabricated on silicon-on-insulator (SOI) wafers. First the fabricated lateral emitters were characterized for emission current scaling to examine the scaling effect of different structures with respect to the forward emission current. Then, two identical diodes were connected in a circuit using diode–resister logic to realize the logic OR function with a square wave as an input signal. The current scaling behavior, demonstrating 1μA current at 18, 15, 7 and 2.2V for 125-, 325-, 2340- and 9360-fingered emitter structures respectively, directly affects the logic OR response. These nanodiamond vacuum logic gates are promising for application in harsh environments.

Half-wave rectification and envelope detection utilising monolithic nanodiamond lateral field emission diode

Successful fabrication and characterisation of a vacuum microelectronic half-wave rectifier and envelope detector using a 2000-fingered nanodiamond lateral field emitter diode with 4 µm inter-electrode spacing is reported. The electrical characterisation demonstrates low turn-on field (∼1.4 V/µm) and high emission current, verified by the Flower-Nordheim plot. The diode is then connected in appropriate circuits to realise half-wave rectification and envelope detection. This approach demonstrates a new way of developing temperature- and radiation-tolerant integrated microelectronics.

Nanodiamond lateral field emission vacuum logic OR gate

Reported are fabrication and characterisation of a novel vacuum logic OR gate using two identical nanodiamond lateral field emission diodes fabricated on silicon-on-insulator wafers. Each diode consists of 9000 finger-like emitters with 4 µm interelectrode spacing. High and stable emission current with low turn-on field have been observed and verified by a Fowler-Nordheim plot for each structure. Diode-resistor logic is used to realise the logic OR function. This nanodiamond vacuum logic gate is very promising for application in harsh environments.

A diamond in the making

Vacuum logic OR gates based on nanodiamond emission devices have been demonstrated by researchers at Vanderbilt University in the US. By fabricating two identical nanodiamond lateral field emission diodes on a silicon-on-insulator wafer, and using diode-resistor logic, they have been able to realise logic devices that have the potential to be used in extreme environment applications.

Development of a vacuum packaged nanodiamond lateral field emission device

The authors report the development of a monolithic diamond field emission device in lateral configuration operating in a vacuum package. Nanocrystalline diamond is applied in the microfabrication of planar lateral emitter diodes on a silicon-on-insulator substrate. A feasible packaging process has been developed for the device, where the diodes are die attached, wire bonded, and vacuum sealed in a cavity package. Field emission characterization measurements performed on the packaged diamond lateral vacuum devices indicate a practical construct and package for vacuum micro/nanoelectronic applications.

Forms and behaviour of vacuum emission electronic devices comprising diamond or other carbon cold cathode emitters

Nanocarbon-derived electron emission devices, specifically nanodiamond lateral field emission (FE) diodes and gated carbon nanotube (CNT) triodes, are new configurations for robust nanoelectronic devices. These novel micro/nanostructures provide an alternative and efficient means of accomplishing electronics that are impervious to temperature and radiation. For example, nitrogen-incorporated nanocrystalline diamond has been lithographically micropatterned to use the material as an electron field emitter. Arrays of laterally arranged 'finger-like' nanodiamond emitters constitute the cathode in a versatile diode configuration with a small interelectrode separation. A low diode turn-on voltage of 7V and a high emission current of 90 microA at an anode voltage of 70V (electric field of approx. 7V microm(-1)) are reported for the nanodiamond lateral device. Also, a FE triode amplifier based on aligned CNTs with a low turn-on voltage and a small gate leakage current has been developed.

Nanodiamond lateral field emitter devices on thick insulator substrates for reliable high power applications

Nanocrystalline diamond field emitter array devices on a thick insulator substrate are being developed for high power applications. These monolithic lateral emitter diodes in comb array configurations demonstrate potential for high emission current applications. A 640 μm-thick aluminium nitride insulating substrate has been integrated with nanodiamond for device electrode isolation. The fabrication process and preliminary field emission characterization results are discussed. The nanodiamond lateral vacuum device may be a superior way to achieve reliable high-speed and high-power electronics.

Field emission devices for advanced electronics comprised of lateral nanodiamond or carbon nanotube emitters

Nanocarbon-derived electron emission devices, specifically, nanodiamond lateral field emission diodes and gated carbon nanotube triodes are new configurations for robust nanoelectronic devices. These novel micro/nanostructures provide an alternative and efficient means of accomplishing electronics that are impervious to temperature and radiation. Nitrogen-incorporated nanocrystalline diamond has been lithographically micropatterned to utilize the material as an electron field emitter. Arrays of laterally arranged “finger-like” nanodiamond emitters constitute the cathode in a versatile diode configuration with small interelectrode separation. Nanodiamond lateral tip conditioning techniques are employed to improve emission and the subsequent device performance discussed. A low diode turn-on voltage of 7 V and a high emission current of 90 μA at an anode voltage of 70 V (electric field of ∼ 7 V/μm) is reported for the nanodiamond lateral device. Also, the development of a field emission triode amplifier based on aligned carbon nanotubes (CNTs) with low turn-on voltage and small gate leakage current, utilizing a dual-mask microfabrication process is reported. The2 × 20 μm CNT triode array displays a gate turn-on voltage of ∼ 44 V, and low gate currents less than 3% of the anode currents. The low gate leakage currents observed confirmed the effectiveness of the convex-shaped gated CNT emitter in alleviating the cathode-gate leakage problem that compromises the operation of a field emission triode.

Emission current scaling in nanodiamond lateral field emission devices

Batch-fabricated lateral fingerlike nanodiamond emitters with sharp apexes were characterized for emission current scaling to examine the scaling effect of the number of emitters with respect to the forward emission current. Three nanodiamond lateral device configurations were evaluated: 6- 125- and 2000-finger emitter structures. Current scaling behavior was observed for a given electric field, e.g., 10V∕μm, demonstrating emission current of 1.1, 11.3, and 109μA, respectively. The augmentation in overall emission current of the multifingered lateral emitters is attributed to the increase in the emitter area and thereby the number of potential emission sites in the cathode. Deviation from ideal scaling, factors contributing to deviation, and the design/process developments addressed to mitigate the nonideality are discussed.

Nanodiamond lateral comb array field emission diode for high current applications

Nanodiamond comb-shaped lateral field emitter arrays in diode configuration were fabricated and characterized for high current field emission. Nitrogen-incorporated nanocrystalline diamond with grain size of 5–10 nm was micropatterned using RIE to realize interconnected arrays of comb structures equipped with uniformly spaced high aspect ratio lateral emitter fingers. A 9000-fingered nanodiamond lateral comb array diode with an inter-electrode spacing of 8 μm demonstrated a high emission current of ∼ 25 mA at an anode voltage of 260 V (electric field ∼ 32 V/μm) in 10 − 7 Torr vacuum. The lateral emitter configuration shows potential for higher power with no emission current saturation observed. These vacuum micro/nanoelectronic devices comprised of nanodiamond lateral field emission diodes are attractive for low-voltage operating high current electron sources, high-power and high-speed switches, and other extreme demand/extreme environment electronics.

Diamond/Carbon Field Emission Based Structures for Sensors and MEMS

Chemical vapor deposited diamond/carbon micro- and nanostructures are excellent field emission cathodes for novel applications in sensors, MEMS, and NEMS because of their low electron affinity and excellent mechanical and chemical properties. However, practical micropatterning and fabrication of emitter structures are needed to fully exploit their potential use. This paper describes the use of microfabrication methods to achieve various forms of morphologically-engineered cathodes such as micro pyramidal tips with self-aligned gated membrane, nano-diamond lateral field emitters with built-in anode, and carbon-nanotube field emission arrays with self-aligned gate. We report the achievement of these micropatterned diamond/carbon field emission-based sensing platforms with excellent field emission characteristics. These field emitter-based microstructures are efficient sensing platforms from which novel sensors and MEMS can be derived.

Nanocarbon field emission devices

AbstractWe are fabricating and examining nanocarbon derived electron emission devices, specifically, nanodiamond lateral field emission diodes and gated carbon nanotube triodes. These novel microstructures provide interesting means of accomplishing electronics that are unaffected by temperature and radiation. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Single-mask multiple lateral nanodiamond field emission devices fabrication technique

We report an efficient microfabrication process technique developed to realize multiple lateral diamond field emitter structures on the same wafer using a single mask. Nanodiamond films with grain size of 5–10nm deposited by CH4∕H2∕N2 microwave plasma enhanced chemical vapor deposition were selectively micropatterned using reactive ion etching at an etch rate of 0.5μm∕min. Several nanodiamond lateral field emission diodes and triodes of different emitter geometries and electrode configurations have been batch fabricated on a silicon-on-insulator wafer. Interelectrode spacing down to 2μm was achieved in arrays of devices on a SiO2 dielectric layer. This fabrication process technique, with its single-mask utility, high manufacturability, combined with its reproducibility, is an efficient and cost-effective approach to realize various configurations of field emission structures in wafer process technology. These nanodiamond vacuum nanoelectronic lateral devices hold high-speed and high-frequency operation potential.