Transport properties of CVD diamond elucidated by DC and AC conductivity measurements

• Published in: Diamond and related materials Vol. 13; no. 2; pp. 277 - 281
• Main Authors: Conte, G, Rossi, M.C, Salvatori, S, Spaziani, F, Vitale, G, Ascarelli, P
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 01.02.2004; Elsevier
• Subjects: Chemical vapor deposition (including plasma-enhanced cvd, mocvd, etc.); Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; DC and AC conductivity; Electron and ion emission by liquids and solids; impact phenomena; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic transport in interface structures; Exact sciences and technology; Impedance spectroscopy; Materials science; Metal-semiconductor-metal structures; Methods of deposition of films and coatings; film growth and epitaxy; Physics; Polycrystalline diamond; Thermionic emission; Transport properties; Polycrystalline diamond; DC and AC conductivity; Transport properties; Impedance spectroscopy; Temperature dependence; Inorganic compounds; Electrical conductivity; Thick films; Diamonds; Polycrystals; Crystal growth from vapors; Experimental study; CVD; Surface conductivity; Activation energy
• ISSN: 0925-9635; 1879-0062
• DOI: 10.1016/j.diamond.2003.11.002

Detailed comprehensive study was carried out on diamond thin films to understand the charge carrier transport with respect to temperature and frequency domain of AC conductivity. Metal-Diamond-Metal structures were used to study the bulk transport and surface conductivity of freestanding films. Large differences were observed between the surface and bulk admittance values of as grown films. Bulk transport resulted in thermally activated behavior both in AC and DC measurements with activation energies of 0.65 eV for thermionic emission of trapped charge. Normalized Cole–Cole plots can be explained on the basis of a superposition of four Voigt elements representing an effective medium constituted by a distribution of grains, elongated in the growth direction, and temperature dependent leakage paths. A simple model of the grain boundary is introduced to discuss and justify the observed results.