Optimization of electrical conductivity of SnS thin film of 0.2 < t ≤ 0.4 μm thicknes for field effect transistor application

Abstract

This study is focused on the investigation of SnS thin film for transistor application. Electron trap which is associated with grain boundary effect affects the electrical conductivity of SnS semiconductor thin film thereby militating the attainment of the threshold voltage required for transistor operation. Grain size and grain boundary is a function of a semiconductor’s thickness. SnS semiconductor thin films of 0.20, 0.25, 0.30, 0.35, 0.40 μm were deposited using aerosol assisted chemical vapour deposition on glass substrates. Profilometry, Scanning electron microscope, Energy dispersive X-ray spectroscopy and hall measurement were used to characterise the composition, microstructure and electrical properties of the SnS thin film. SnS thin films were found to consist of Sn and S elements whose composition varied with increase in thickness. The film conductivity was found to vary with grain size and grain boundary which is a function of the film thickness. The SnS film of 0.4 μm thickness shows optimal grain growth with a grain size of 130.31 nm signifying an optimum for the as deposited SnS films as the larger grains reduces the number of grain boundaries and charge trap density which allows charge carriers to move freely in the lattice thereby causing a reduction in resistivity and increase in conductivity of the films which is essential in obtaining the threshold voltage for a transistor semiconductor channel layer operation. The carrier concentration of due to low resistivity of 3.612 ×105 Ωcm of 0.4 μm SnS thin film thickness is optimum and favours the attainment of the threshold voltage for a field effect transistor operation hence the application of SnS thin film as a semiconductor channel layer in a field effect transistor.

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“…As a result, these defects act as dispersion centers, increasing the resistivity of the films. These findings are consistent with those reported by Daniel et al [23].…”

Morphology and Crystal Structure of Cu2NiSn(S,Se)4 Thin Films Obtained by an Electrodeposition-Annealing Process

“…For example, in [37], for the Cd 1−x Zn x S films, the dependence of the electrical conductivity on the grain size was shown, and it was found that the electrical conductivity had a maximum for the film with a grain size of about 36.445 nm (5 × 10 -10 (Ω•m) -1 ). The electrical conductivity of SnS films with crystallites of 55.05 nm is 2.364 × 10 -7 (Ω•cm) −1 (δ = 3.30 × 10 14 m -2 and ε = 2.31 × 10 -3 ) [38].…”

“…The crystallite size (D) of the CNTSSe films was determined from the Scherrer equations as follows [37,38]:…”

“…where λ is the x-ray wavelength; β is the full width of the peak at half maximum (FWHM); θ is the Bragg angle (in radian). Dislocation density (δ) and microstrain (ε) were calculated using Equations ( 2) and (3), respectively [38].…”