Temperature-Dependent Impedance Spectra of Nitrogen-Doped Ultrananocrystalline Diamond Films Grown on Si Substrates

IEEE Access

Abdelrahman Zkria¹  Tsuyoshi Yoshitake¹  Mahmoud Shaban² 

[1] Department of Applied Science for Electronics and Materials, Kyushu University, Fukuoka, Japan;Department of Electrical Engineering, College of Engineering, Qassim University, Unaizah, Saudi Arabia;

关键词: Nitrogen-doping;    coaxial arc plasma gun;    complex impedance spectroscopy;    nanodiamond grains;    grain boundaries;   

DOI  :  10.1109/ACCESS.2020.3046969

来源: DOAJ

【 摘 要 】

Nitrogen-doped ultrananocrystalline diamond/hydrogenated amorphous-carbon (UNCD/a-C:H) composite films, grown on Si substrates by the coaxial arc plasma gun, were investigated using temperature-dependent impedance spectroscopy. The measurements were carried out in frequency and temperature ranges of 100 Hz-2 MHz and 300-400 K, respectively. Structurally, the nitrogen incorporation into the deposited films as well as sp²/sp³ ratio was studied by X-ray photoemission spectroscopy (XPS), measured with synchrotron radiation. The results of temperature-dependent electrical conductance characterization of the examined films revealed that the heterogeneous structure possesses a low-frequency conduction mechanism with an activation energy of 46 meV. This possibly originated from charge carriers hopping in the deposited composite. Furthermore, the results manifested a relaxation process, with an activation energy of 41 meV, originated from space charges in grain boundaries of the films. Cole-Cole plots of measured and fitted impedance spectra exhibited equivalent resistance due to grain boundaries that are much smaller than that related to UNCD grains. This is owing to the nitrogen incorporated in the composite film inside the grain boundaries instead of the grains. This increases the concentration of charge carriers within the grain boundaries and therefore enhances their conductivity. Moreover, the deduced capacitance corresponding to grain boundaries was larger than that originated from the UNCD grains. This is due to the difference between the grain-size and grain-boundary width of the UNCD/a-C:H composite.

【 授权许可】

Unknown