Synthesis of a Family of ([SnSe] sub(1+ delta )) sub(m)-([{Mo sub(x)Nb sub(1x)}Se sub(2)] sub(1+ gamma ) ) sub(1)[SnSe] sub(1+ delta )) sub(m)-({ Nb sub(x)-Mo sub(1-x)}Se sub(2)) sub(1) Superlattice -Heterostructures (m = 0, 1, 2, 3, 4 -and 0.8 less than or equal to x less than or equal to 1

• Published in: European journal of inorganic chemistry 2016-03, Vol.2016 (8), p.1225-1231
• Main Authors: Westover, Richard D, Mitchson, Gavin, Ditto, Jeffrey J, Johnson, David C
• Format: Article
• Language: English
• Subjects: Alloying; Carrier density; Diffusion length; Heterostructures; Nanostructure; Niobium; Precursors; Self assembly
• ISSN: 1434-1948; 1099-0682
• DOI: 10.1002/ejic.201501324

A family of multiple-component heterostructures, ([SnSe] sub(1+ delta )) sub(m)([{Mo sub(x)Nb sub(1-x)}Se sub(2)] sub(1+ gamma )) sub(1)([SnSe] sub(1+ delta )) sub(m)({Nb sub(x)Mo sub(1-x)} Se sub(2)) sub(1) (m = 0, 1, 2, 3, 4 and 0.8 less than or equal to x less than or equal to 1), was self-assembled from designed amorphous precursors, and their structure and physical properties were characterized. The compounds consist of MoSe sub(2) and NbSe sub(2) layers with metal centers in a trigonal-prismatic environment interleaved with systematically increasing numbers of SnSe bilayers with a distorted rock salt structure. The extent of alloying of the miscible dichalcogenide constituents decreased from about 20% for m = 0 to less than 1% for m = 3 and 4. The decreased alloying with increased SnSe thickness suggests the diffusion lengths of Mo and Nb during self-assembly are about a nanometer. Resistivity and Hall coefficient measurements show that the electrical transport properties are similar to those of ([SnSe] sub(1+ delta )) sub(m)(NbSe sub(2)) sub(1) (m = 1-8) compounds, suggesting that the NbSe sub(2) layer dominates the conductivity and that charge transfer from SnSe reduces the carrier concentration in the NbSe sub(2) layer. A family of heterostructures, consisting of MoSe sub(2) and NbSe sub(2) layers interleaved with systematically increasing numbers of SnSe bilayers, self-assembled from designed amorphous precursors. Decreased alloying with increasing thickness of the interleaving SnSe layers suggests the diffusion lengths of Mo and Nb during self-assembly are about a nanometer.