M. Gurubhaskar; Narayana Thota; A.C. Kasi Reddy; Y.P. Venkata Subbaiah
Abstract
Tin mono-sulfide thin films were prepared using a two-step process consisting of DC sputtered deposition of Sn precursors over glass substrate held at 150 oC, followed by sulfurization for 1 hour at different temperatures ranging from 250 oC to400 oC. The influence of the sulfurization temperature on ...
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Tin mono-sulfide thin films were prepared using a two-step process consisting of DC sputtered deposition of Sn precursors over glass substrate held at 150 oC, followed by sulfurization for 1 hour at different temperatures ranging from 250 oC to400 oC. The influence of the sulfurization temperature on resultant films was studied in terms of its structure, morphology and opto-electronic properties. X-ray diffraction study revealed that the films sulfurized at lower temperature (~250 oC) had prominent SnS2 phase in addition to SnS. A single-phase tin mono-sulfide planes corresponding to orthorhombic structure has been observed at 300 oC and found to be highly crystalline at 350 oC. Further, three distinct Raman modes observed at 95, 190 and 218 cm-1 for Sn precursors sulfurized at 350 oC, strongly supporting the formation of single phase SnS. The optimized SnS film showed a direct band gap of 1.35 eV with an absorption coefficient of 5 x 104 cm-1. The valence states of Sn (+2) and S (-2) determined from X-ray photoelectron spectroscopy analysis for Sn precursors sulfurized at 350 oC, indicating the existence of SnS. These films had stoichiometric atomic ratio of Sn/S ~ 1 with surface roughness of 20 nm. All the films have shown p-type conductivity and the Sn precursors sulfurized at 350 oC exhibited relatively high conductivity of 0.947 x 10-2 (Ω cm)-1. The optoelectronic properties of SnS films reported in the present work would be highly suitable for device fabrication and promising as an alternative absorber for thin film solar cells. Copyright © 2017 VBRI Press.
Sangeeta Semwal; Sarab P. Singh; Vasant D. Vankar
Abstract
In present work, hybrid structures of Si Nanocrystals (Si-ncs) and Carbon Nanotubes (CNTs) with bead-like architecture have been synthesized by exposing pristine CNTs to silane (SiH4) at 200 ºC. The exposed CNTs were annealed in Ar ambient at 500ºC in a catalytic chemical vapor deposition chamber. ...
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In present work, hybrid structures of Si Nanocrystals (Si-ncs) and Carbon Nanotubes (CNTs) with bead-like architecture have been synthesized by exposing pristine CNTs to silane (SiH4) at 200 ºC. The exposed CNTs were annealed in Ar ambient at 500ºC in a catalytic chemical vapor deposition chamber. High-resolution transmission electron microscopy (HRTEM) elucidated that the bead-like architecture has well-defined crystalline nature. X-ray photoelectron spectroscopy (XPS) was used to study the nature of chemical bonding and structural functionalization/defects caused by silane exposure and annealing on the nanotube surface. XPS results indicated in-diffusion of Si in the CNT cavity as well reduction in oxygen content on the top surface of the CNTs. X-ray diffractometry was used to further confirm the formation of the crystalline hybrid structures. From the present work it is inferred that a controlled synthesis of hybrid structures (CNT-Si ncs) with bead-like architecture can be achieved by a simple CVD method for various applications