Control of physical vapor deposition and architecture of stoichiometric SnSe heterojunction structures for solar cells

Abstract Systematic investigations on microstructural development during the physical vapor deposition of SnSe thin films under high vacuum (10−6 mbar) on glass substrates have been carried out, so as to mold the functional properties for fabrication of novel Au/MoO3/p-SnSe/n-CdS/ITO/SLG heterojunction solar cells. Stoichiometric SnSe crystalline target was prepared using a muffle furnace integrated with an indigenously assembled rotation mechanism and its vapors were condensed by subjecting to facile thermal evaporation process, without any extraneous chemical precursors. Effect of substrate temperature, TS (27–350 °C) on morphology, growth mechanism and lattice periodicity was analyzed with the aid of FESEM, AFM and XRD. Fine tuning of TS (= 250 °C) enabled atomically smooth surfaces with appreciable crystallinity and resulted in orthorhombic structure having preferred orientation of crystallites along (111) direction, devoid of other phases. Chemical homogeneity and phase purity were justified by EDAX, XPS and Raman spectroscopy. The values of band gap, electrical resistivity, mobility and concentration of charge carriers are equal to 1.48 eV, 2.36 Ωcm, 6.36 cm2V−1s−1 and 1.25 × 1018 cm−3 respectively. The attained efficiency (1.39%) of the prepared photovoltaic device promises the versatility of SnSe absorber layers towards the enhancement of solar energy conversion.