Electrical characterization of Ag/MoO_3−x/p-Si Schottky diodes based on MoO_3−x synthesized via sol–gel method: an investigation on frequency and voltage dependence

MoO_3−x is a commonly used buffer layer in organic based optoelectronic devices to align energy level between active semiconductor and metal layer. The purpose of this study is to show the effects of the MoO_3−x interlayer by comparing with a reference device without MoO_3−x interlayer. To evaluate the effect of MoO_3−x interlayer synthesized by sol–gel method, basic important parameters such as ideality factor (n), barrier height ( \(\varnothing\) $\varnothing$ _B), interface states (N_ss) and series resistance (R_s) of Ag/MoO_3−x/p-Si and Ag/p-Si Schottky diodes were calculated by electrical characterization methods. The current–voltage (I–V) measurements show that the ideality factor for the p-Si/Ag reference diode was decreased from 2.4 to 1.9 while rectification factor increasing 44.6 times using MoO_3−x interlayer, and frequency–dependent measurements (C–V–f, G–V–f) were carried out to elucidate this deviation at room temperature for MoO_3−x-based diode. From the XPS analysis, it was seen that Mo⁺⁶ and Mo⁺⁵ oxidation states were intense on the surface of the MoO_3−x film, and the Mo⁺⁴ oxidation state increased as it went into the bulk. The changes in R_s and N_ss due to the energy levels formed by the Mo⁺⁶ and Mo⁺⁵ oxidation steps at the interface are depicted. In addition, the energy density distribution profile of N_ss was obtained using the I–V characteristics for various forward bias voltages range from 2.1 × 10¹² to 2.5 × 10¹² eV⁻¹ cm⁻². Based on the experimental results, the sol–gel synthesized MoO_3−x thin film exhibits favorable rectification characteristics and holds promise for application as a Schottky diode.