Microstructural and electronic properties of rapid thermally grown MoS$_2$|silicon hetero-junctions with various process parameters

Molybdenum disulphide (MoS$_2$) has gained tremendous attention due to its tunable semiconducting properties and versatile applications in future electronic and optoelectronic devices. Here, MoS$_2$ thin films were grown by adopting rapid thermal process. The process parameters like time and temperature have been systematically varied to modulate the morphological, microstructural, and electronic properties of MoS$_2$ thin films. A uniform morphology has been observed from FESEM images. The microstructural study was further carried out using XRD pattern and Raman spectra. The intensity of (002) XRD characteristic peak at 2$\theta$ = 14.1$^\circ$ is found to be increased, whereas the FWHM values are reduced with the growth time and process temperature. The improvement of crystallinity of the MoS$_2$ thin films with growth temperature is attributed to the decrease in the FWHM values of the characteristic Raman peaks, E$^1_{2g}$ and A$_{1g}$. The dependence of hetero-junction characteristics such as ideality factor $\eta$, built-in voltage $V_{\mathrm{bi}}$, and carrier concentration on the growth parameters was evaluated using current–voltage and capacitance–voltage measurements. The films grown at 900$^\circ$C for 5 min. have possessed carrier concentration of 5.21 $\cdot$ 10$^{16}$ cm$^{-3}$, with 0.55 V as $V_{\mathrm{bi}}$, and $\eta$ is found to be 2.04 for MoS$_2$|Si hetero-junction. The decrease in the carrier concentration, $\eta$, and $V_{\mathrm{bi}}$ in MoS$_2$|Si hetero-junction with the increase in the growth temperature has been ascribed to the reduction in the defect states due to enhancement in the sulfurization.