Dependence of ac electrical resistivity on the thickness of the DLC layer in In/DLC//Si/In nanostructure

As the thickness of the DLC layer increased from 22 to 46 nm, a corresponding rise in number of carbon atoms with the $sp^2$ hybridization of electron orbitals from 9% to 21% was observed, by analyzing the X-ray photoelectron spectroscopy (XPS) measurements. Moreover, negligible nitriding and oxidation of the DLC surface was confirmed via X-ray photoelectron spectroscopy. An equivalent electrical circuit is proposed to describe the impedance frequency dependences of the DLC coating as well as the potential barrier at the DLC//Si interface. In the quasistatic limit, the resistivity of the DLC layer decreases from 1000 to 1 $\Omega$ $\cdot$ cm as the thickness increases from 22 to 71 nm. It has been demonstrated that the impedance of the In/DLC//Si/In structure can change by a factor of 20 when the bias voltage varies between -4 $\dots$ 4 V relative to the Si substrate.