On the energy distribution profile of interface states obtained by taking into account of series resistance in Al/TiO2/p–Si (MIS) structures

The energy distribution profile of the interface states (Nss) of Al/TiO2/p–Si (MIS) structures prepared using the sol–gel method was obtained from the forward bias current–voltage (I–V) characteristics by taking into account both the bias dependence of the effective barrier height (ϕe) and series resistance (Rs) at room temperature. The main electrical parameters of the MIS structure such as ideality factor (n), zero-bias barrier height (ϕb0) and average series resistance values were found to be 1.69, 0.519 eV and 659 Ω, respectively. This high value of n was attributed to the presence of an interfacial insulator layer at the Al/p–Si interface and the density of interface states (Nss) localized at the Si/TiO2 interface. The values of Nss localized at the Si/TiO2 interface were found with and without the Rs at 0.25-Ev in the range between 8.4×1013 and 4.9×1013 eV−1 cm−2. In addition, the frequency dependence of capacitance–voltage (C–V) and conductance–voltage (G/ω–V) characteristics of the structures have been investigated by taking into account the effect of Nss and Rs at room temperature. It can be found out that the measured C and G/ω are strongly dependent on bias voltage and frequency.

Research highlights►We successfully fabricated Al/TiO2/p-Si device with interlayer by a sol-gel method. The facts: (i) that the technology of the fabrication of a Al/TiO2/p-Si MIS structure much simpler and economical than that for the Si p-n junction and (b) the main advantages of TiO2 films are low densities of the surface states when compared to SiO2.