Nanocrystalline diamond as an electronic material: An impedance spectroscopic and Hall effect measurement study

Abstract

Nanocrystalline diamond (NCD) has been grown using a nanodiamond seeding technique, leading to a dense form of this material, with grain sizes around 100 nm. The electrical properties of both intrinsic and lightly boron-doped NCD have been investigated using impedance spectroscopy and Hall effect measurements. For intrinsic material, both grain boundaries and grains themselves initially contribute to the frequency dependant impedance values recorded. However, boundary conduction can be removed and the films become highly resistive. Interestingly, the ac properties of these films are also excellent with a dielectric loss value ∼0.004 for frequencies up to 10 MHz. The dielectric properties of these NCD films are therefore as good as high quality large grain polycrystalline diamond films. In the case of boron-doped material, p-type material with good carrier mobility values (10–50 cm2/V s) can be produced at carrier concentrations around 1017 cm−3.

An insight of p-type to n-type conductivity conversion in oxygen ion-implanted ultrananocrystalline diamond films by impedance spectroscopy

“…They are nearly the same at high frequency, meaning that the conductive behaviour in this region is quite similar in these samples. The low frequency impedance values of O12 series samples, sample 900-A and as-deposited sample are in the range of 10 4 -10 5 Ω, which are several orders of magnitude smaller than those of nanocrystalline diamond films (10 6 Ω), 26 detonation nanodiamonds (10 9 Ω) 33 and phosphorus-doped single crystalline diamond film (10 9 Ω) 34 at room temperature. This means that UNCD films are more conductive.…”

“…It has also been used to characterize the conduction paths in polycrystalline, nanocrystalline diamond films and diamond MOS structures at various biases. [23][24][25][26][27] Here, IS and temperature dependent current-voltage (I-V) technique were used to understand the conduction mechanism and obtain the inherent insight of conductivity transition in O + -implanted UNCD films. This has significance in the preparation of nanocrystalline diamond based devices.…”

The CVD of Nanodiamond Materials

“…[50] A strategy employed to achieve high quality NCD is to seed a substrate with at least a monolayer of the smallest diamonds available (currently the explosively formed nanodiamond powder, ultradisperse diamond (UDD), [5,94,95] then grow homoepitaxially on these seeds under highquality diamond CVD conditions (very low carbon content in the reactants). [50] This high-quality NCD (as determined by optical, [57,96] electrical, [97,98] and mechanical properties [50] ) is grown in 600-1200 W microwave plasmas with 0.1-0.3% CH 4 in H 2 under 5-30 Torr pressure, and a substrate temperature between 400 and 900 8C. Membranes and structures as thin as 30 nm can be fabricated from these films by etching away the substrate or supporting materials.…”

“…[97,130] Boron doping of NCD is achieved by the addition of gaseous boron compounds, such as diborane or trimethylborane, to the growth chemistry. The boron levels can range from <10 15 cm À3 to over 10 21 cm À3 [98,131] with conductivities up to 0.1-1 S m…”

Hydrogen-terminated detonation nanodiamond: Impedance spectroscopy and thermal stability studies

“…39 Hence, we associated that the capacitance with the grain boundaries conduction contribution for H-DND.…”