Frequency-dependent electrical parameters and extracted voltage-dependent surface states in Al/DLC/p-Si structure using the conductance method

Abstract

In the present work, a diamond-like carbon film (DLC) was electrodeposited on a p-Si substrate and was used to fabricate an Al/DLC/p-Si/Au metal/interlayer/semiconductor (MIS) Schottky diodes (SDs). The structural analysis of the DLC interfacial layer produced by the electrochemical method were done using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) methods. The SEM images showed that the silicon surface was completely coated with DLC film and spherical particles and islets appeared on the film surface. The XPS spectrum showed that the film mainly consists of C and O elements. The frequency/voltage-dependent capacitance and conductance measurements of the fabricated electronic device were made between 1 to 1 MHz and − 1 V to 4 V, respectively. The slope and intercept of the linear part of the C⁻² plot are used to extract the main electrical parameters of the structure, e.g., diffusion potential $({V}_{D})$, doping concentration of acceptor atoms $({N}_{A})$, Fermi energy $({E}_{F})$, maximum electric field $({E}_{m})$, depletion layer width $({W}_{D})$, and barrier height $({\Phi }_{B})$. Furthermore, the density of surface states $\left({N}_{\mathrm{ss}}\right)$ and the lifetime of the charges in the states $\left(\tau \right)$ are calculated from the parallel conduction method and these values vary from $3.8\times {10}^{11}$ to $7.2\times {10}^{11}{\mathrm{eV}}^{-1}{\mathrm{cm}}^{-2}$ and $140$ to $4.7\mathrm{ \mu s}$, respectively. The lower magnitude of the ${N}_{\mathrm{ss}}$ arises from the passivation effect of the DLC interlayer. As a result, the DLC film showed outstanding characteristics as an interlayer and, therefore, has potential usage instead of oxide or other insulator layers for the purpose of decreasing the ${N}_{\mathrm{ss}}$ and other dislocations in SDs.