## 3 Synthetic Routes to SnS
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Phase** & **Temperature Gradient (\({}^{\circ}\)C)** & **Stoichiometric Ratio Sn:S** & **Time (Days)** \\ \hline SnS & 850–950 & 0.90:1 & 10 \\ \hline SnS\({}_{2}\) & 600–850 & 0.51:1 & 12 \\ \hline Sn\({}_{2}\)S\({}_{3}\) & 500–650 & 0.67:1 & 10 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Reaction conditions used to synthesise the phases of tin sulfide using CVT [41], adapted with permission from _Chem. Mater._**2013**, _24_, 4908–4916. deposition was performed without any external sulfur source or co-reagents including H\({}_{2}\)S gas, which is a well-cited advantage of the use of single source precursors such as these. Rietveld analysis of the powder XRD patterns of the produced thin films confirmed the presence of orthorhombic SnS (herzenbergite) as the main phase with smaller amounts of SnO\({}_{2}\) present at all deposition temperatures. The existence of SnO\({}_{2}\) is believed to be due the aerial oxidation of tin precursors because the samples were handled in an atmospheric environment, although this explanation seems at odds with the tin centre being in oxidation state IV. Depending on the deposition temperature and type of precursor used, a range of strongly adherent SnS thin films of different colours were obtained, such as dense brownish-yellow, dark-black, and dark-brownish. In Figure 2, energy-dispersive X-ray (EDX) spectroscopy showed variation in the atomic percentage of tin and sulfur, clearly indicating the sulfur-deficient system with a small amount of carbon contamination in the film [44]. Additionally, a wide range of band gap energies were reported, which suggests that the films were very much different in their composition depending on the synthesis conditions employed. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Precursor**} & \begin{tabular}{c} **Deposition** \\ **Temperature** \\ **(\({}^{\circ}\)C)** \\ \end{tabular} & \begin{tabular}{c} **Carrier** \\ **Concentration,** \\ **\(\mathbf{p}\) **(\(\times\) 10\({}^{18}\) cm\({}^{-3}\))** \\ \end{tabular} & \
\begin{tabular}{c} **Resistivity,** \\ **\(\mathbf{\rho}\) **(\(\Omega\) cm)** \\ \end{tabular} &
\begin{tabular}{c} **Mobility,** \\ **(cm\({}^{2}\) V\({}^{-1}\) s\({}^{-1}\))** \\ \end{tabular} \\ \hline
**1** & 500 & 4.13 \(\times\) 10\({}^{17}\) & 10.8 & 1.4 \\ \hline
**2** & 530 & 3.60 \(\times\) 10\({}^{18}\) & 1.58 & 1.1 \\ \hline
**3** & 450 & 8.64 \(\times\) 10\({}^{18}\) & 0.83 & 0.87 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Electrical properties of tin sulfide films deposited from precursor **(1)** at 500 \({}^{\circ}\)C and precursor **(2)** at 530 and 450 \({}^{\circ}\)C [44]. Adapted with permission from _Chem. Mater._**2013**, 3, 266–276. Figure 2: SEM images of SnS films deposited by aerosol-assisted chemical vapour deposition (AACVD) on glass substrates using [Sn(C\({}_{4}\)H\({}_{0}\))\({}_{2}\)(S\({}_{2}\)CN(C\({}_{2}\)H\({}_{5}\))\({}_{2}\))\({}_{2}\)] at **(a)** 450 \({}^{\circ}\)C and **(b)** 500 \({}^{\circ}\)C; SEM images of SnS films deposited on glass substrates by AACVD from [Sn(C\({}_{4}\)H\({}_{0}\))\({}_{2}\)(S\({}_{2}\)CN(CH\({}_{3}\))(C\({}_{4}\)H\({}_{0}\))\({}_{2}\)] at **(c)** 450 \({}^{\circ}\)C and **(d)** 500 \({}^{\circ}\)C [44]. Adapted with permission from _Chem. Mater._**2013**, 3, 266–276. [PERSON] et al. reported the deposition of SnS thin films on glass substrates using AACVD at 450 \({}^{\circ}\)C and 500 \({}^{\circ}\)C by dissolving unsymmetrical dithiocarbamates of tin(II) of the formula [Sn(S\({}_{2}\)CNRR\({}^{\prime}\))\({}_{2}\)], where RR' denotes the different alkyl groups. Grey adherent films of the orthorhombic SnS phase were obtained in all the cases, with the exception of additional peaks occurring around 20 = 33.50\({}^{\circ}\), which again was assigned to cassiterite SnO\({}_{2}\). Near-stoichiometric SnS films are obtained at higher concentrations (150 mM) of precursors and at 450 \({}^{\circ}\)C [45]. [PERSON] et al.