Impact of electrical resistance and TEP in layered SnSe crystals under high pressure

Abstract

SnSe crystals belong to IV-VI layered binary semiconducting compound category. These layered compounds have generated a great deal of interest due to their interesting electronic properties. These electronic materials are useful because of their applications in holographic-recording systems, optoelectronics and memory switching. Earlier, several investigators have studied and reported the influence of temperature and pressure over the phase transitions in SnS and SnSe semiconductors. They also utilized Mossbauer Spectroscopy and Hydrostatic Pressure techniques to examine the bonding of the Sn atoms in SnS and SnSe. It is therefore thought worthwhile to study the effect of pressure on the thermoelectric power and the electrical resistance of SnSe crystals synthesized by a modified direct vapour transport technique. The electrical resistance has been found to be pressure dependent. The transition in electrical resistance behaviour, observed at 65 Kbar, has been explained on the basis of transition from a predominantly two-dimensional material to a more threedimensional one. Similar to the resistance behaviour, the thermoelectric power is also found to be pressure dependent. The increase in thermoelectric power with pressure at the transition pressure of 65 Kbar has been explained. The implications are discussed.

On the band gap location and core spectra of orthorhombic IV–VI compounds SnS and SnSe

“…In particular, SnS and SnSe have been used as shells for PbSe and PbS quantum dots, for the development of infrared-based devices [5], and as alternative for Cadmium in IR thin film coatings [6]. Although SnS and SnSe have been experimentally and theoretically assessed [7][8][9][10][11][12][13][14][15][16], we present results that to the best of our knowledge were not reported before.…”

Structural changes in thermoelectric SnSe at high pressures

“…They found its electronic properties to be three-dimensional in nature, already at ambient pressure, as opposed to the two-dimensional nature suggested by the easy cleavage of SnSe crystals, their lattice dynamics [12] and the interpretation of the chemical bonding in this compound [5]. Agarwal et al [13,14] observed abrupt changes in the electrical resistivity and thermopower near 6 GPa, but their exact origin has remained unclear. Interestingly, the resistivity decreases monotonically with increasing pressure, whereas the thermopower decreases up to 6.3 GPa, followed by large enhancement between 6.5 and 7.6 GPa.…”

Effects of Annealing on Thermally Evaporated SnSe Thin Films

“…It has great potential in memory switching devices [2], solar cells [3], holographic recording systems [4], radiation detectors [5] and opto-elecronic devices [6]. The electrical resistance of SnSe semiconducting single crystals is pressure dependent [7]. Preparation of SnSe thin films was reported from various experimental techniques [8][9][10][11][12][13].…”