Abstract
We investigated the effect of Indium (In) doping on the structural and electrical properties of Ti/Au/TiO2:In/n-Si metal-oxide-semiconductor (MOS) devices. Sputtering grown TiO2 thin films on Si substrate were doped using two In-films with 15 nm and 50 nm thicknesses leading to two structures named Low Indium Doped (LID) sample and High Indium Doped (HID) sample, respectively. XRD analysis shows no diffraction pattern related to Indium indicating that In has been incorporated into the TiO2 lattice. Current-Voltage (I-V) characteristics show that rectification ratio at 2 V is higher for HID sample than for LID sample. Evaluated barrier height, ϕB0, decreased while the ideality factor, n, increased with decreasing temperature. Such behavior is ascribed to barrier inhomogeneity that was assumed to have a Gaussian Distribution (GD) of barrier heights at interface. Evidence of such GD was confirmed by plotting ϕB0 versus n. High value of mean barrier ϕ¯B0 and lower value of standard deviation (σ) of HID structure are due to indium doping which increases the barrier homogeneities. Finally, estimated Richardson constants A* are in good agreement with theoretic values (112 A/cm2K2), particularly, for the HID structure.
[Display omitted]
•Study of Indium doping impact on Ti/Au/In-doped-TiO2/n-Si structures.•XRD shows that Indium has been totally incorporated into TiO2 thin films.•Interface inhomogeneity shows a Double Gaussian distribution of barrier heights.•Indium content improved device electrical properties and interface homogeneity.•Estimated Richardson constants are in good agreement with theoretical values.