One-step growth of thin film SnS with large grains using MOCVD

Figures & data

Figure 1. SEM images of film deposited using optimised growth parameters at different growth temperatures: (a) 432 °C; (b) 472 °C.

Figure 2. Sn-S phase diagram taken from Ref. [17].

Notes: Reprinted from R.E. Banai, M.W. Horn and J.R.S. Brownson, A review of tin (II) monosulfide and its potential as a photovoltaic absorber, Sol. Energy Mater. Sol. Cells 150 (2016) 112–129, with permission from Elsevier.

Table 1. Atomic weight (at. %) composition determined by EDX for films deposited using different S/Sn precursor partial pressure ratios, [S/Sn]ⁱ.

Sample	T^oC	DtBS (atm)	TET (atm)	[S/Sn]^i	S at.%	Sn at.%
TS131	472 ± 1	2.91 × 10^−3	7.20 × 10^−4	4.0	43.1	56.9
TS130	472 ± 1	3.26 × 10^−3	6.56 × 10^−4	5.0	47.6	52.4
TS117	465 ± 1	3.40 × 10^−3	6.30 × 10^−4	5.4	49.7	50.3
TS124	472 ± 1	3.65 × 10^−3	5.85 × 10^−4	6.2	50.6	49.3
TS129	473 ± 3	3.83 × 10^−3	5.50 × 10^−4	7.0	51.4	48.6
TS118	469 ± 1	4.05 × 10^−3	5.09 × 10^−4	8.0	52.5	47.5

Figure 3. Absorption spectra of films deposited at different [S/Sn]ⁱ at a growth temperature of 470 °C.

Figure 4. Band gap calculation of films deposited at different [S/Sn]ⁱ using absorption coefficient × energy squared versus energy, (αE)² vs. E, for direct ($E_g^d$) transitions and the square route of absorption coefficient × energy versus energy, (αE)^1/2 vs. E, for indirect ($E_g^i$) transitions (inset).

Figure 5. XRD of films deposited at 470 °C using different [S/Sn]ⁱ equal to 5.4, 6.2 and 8.0, which showed cross-over of SnS 1:1 stoichiometry determined from EDX measurements.

Note: A film deposited at 432 °C and [S/Sn]ⁱ equal to 6.2 is included for comparison.

Figure 6. Raman spectroscopy of different film regions for SnS samples deposited at optimised growth parameters on (a) ITO mapped at a 304 cm⁻¹ frequency and (b) Mo mapped at a 193 cm⁻¹ frequency.

Banai RE , Horn MW , Brownson JRS . A review of tin (II) monosulfide and its potential as a photovoltaic absorber. Sol Energy Mater Sol Cells. 2016;150:112–129.10.1016/j.solmat.2015.12.001

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