Electrical and dielectric parameters in TiO2-NW/Ge-NW heterostructure MOS device synthesized by glancing angle deposition technique

Abstract

Abstract This paper reports the catalyst-free coaxial TiO2/Ge-nanowire (NW) heterostructure synthesis using the glancing angle deposition (GLAD) technique integrated into an electron beam evaporator. The frequency and voltage dependence of the capacitance–voltage (C–V) and conductance–voltage (G/ω–V) characteristics of an Ag/TiO2-NW/Ge-NW/Si device over a wide range of frequency (10 kHz–5 MHz) and voltage (− 5 V to + 5 V) at room temperature were investigated. The study established strong dependence on the applied frequency and voltage bias. Both C–V and G/ω–V values showed wide dispersion in depletion region due to interface defect states (Dit) and series resistance (Rs). The C and G/ω value decreases with an increase in applied frequency. The voltage and frequency-dependent Dit and Rs were calculated from the Hill-Coleman and Nicollian–Brews methods, respectively. It is observed that the overall Dit and Rs for the device decrease with an increase in the frequency at different voltages. The dielectric properties such as dielectric constant ( $$\upepsilon$$ ϵ ′), loss ( $$\upepsilon$$ ϵ ″) and loss tangent (tan δ) were determined from the C–V and G/ω–V measurements. It is observed that $$\upepsilon$$ ϵ ′, $$\upepsilon$$ ϵ ″ decreases with the increase in frequency. Therefore, the proposed MOS structure provides a promising alternative approach to enhance the device capability in the opto-electronics industry.