Chemical vapour deposition of antimony chalcogenides with positional and orientational control: precursor design and substrate selectivity

A series of alkylchalcogenostibines, Me 2 SbSe n Bu, MeSb(Se n Bu) 2 , Sb(Se n Bu) 3 and MeSb(Te n Bu) 2 , have been designed and synthesised as potential precursors for chemical vapour deposition (CVD) by reaction of n BuELi (E = Se, Te) with the appropriate halostibine, Me 3−n SbCl n ( n = 1, 2, 3), and characterised by 1 H, 13 C{ 1 H} and 77 Se{ 1 H} or 125 Te{ 1 H} NMR spectroscopy as appropriate. MeSb(Se n Bu) 2 and MeSb(Te n Bu) 2 are very effective single source precursors for the low pressure CVD of high quality crystalline thin films of Sb 2 Se 3 and Sb 2 Te 3 , respectively, confirmed by scanning electron microscopy, energy dispersive X-ray spectroscopy, Raman spectroscopy and thin film X-ray diffraction. Hall conductivity, carrier mobility, carrier density and, in the case of Sb 2 Te 3 , Seebeck coefficient measurements reveal electronic characteristics comparable with Sb 2 E 3 deposited by atomic layer deposition or molecular beam epitaxy, suggesting materials quality and performance suitable for incorporation into electronic device structures. Choice of substrate and deposition conditions were found to significantly affect the morphology and preferred orientation of Sb 2 Te 3 crystallites, enabling deposition of films with either 〈1 1 0〉 or 〈0 0 1〉 alignment. Use of micro-patterned substrates allowed selective deposition of crystalline 2D micro-arrays of Sb 2 Te 3 onto exposed TiN surfaces only.