Influence of thickness of the sputtered diamond-like carbon (DLC) on electronic and dielectric parameters of the Au/DLC/n-Si heterojunction

The electrical and dielectric properties of the Au/DLC/n-Si heterojunction were investigated in detail by coating the diamond-like carbon (DLC) layers of different thicknesses on Si by the magnetron sputtering. The influence of DLC thickness on the Au/DLC/n-Si heterojunction is the main objective of the study. For this purpose, the current–voltage measurements of the heterojunction were performed as a function of the thickness (10 (D1), 20 (D2), and 50 nm (D3) DLC layer) and it was seen that the device with 50 nm thickness had the best rectifying property (the lowest ideality factor) and stable reverse current, the lowest interface states, the highest dielectric parameter (K), and shunt resistances. And then the capacitance/conductance versus voltage measurements of the heterojunctions were carried out to determine the electrical and dielectric properties of the devices at 500 kHz applied frequency. Some improvements in the high dielectric parameter D3 device were attributed to further limitation of the leakage current. The experimental results suggested that both the complex dielectric parameter (K^∗) and loss tangent (tan δ) were a function of the bias voltage and frequency due to the existence of the surface states and dipole polarizations. Experimental results showed that the DLC layer causes surface passivation on Si, resulting in improved device with increasing thickness, and the DLC/n-Si device is a candidate device for high voltage applications.