Synthesis, growth mechanism and physical properties of vapour-deposited GaTe platelets

Abstract

The physical vapour deposition (PVD) method has been employed to yield gallium telluride (GaTe) platelets. The morphology and growth mechanism of these platelets were investigated with the aid of scanning electron micrographs. The stoichiometry and homogeneity of the grown samples were confirmed by chemical analysis. The X-ray diffraction (XRD) technique has been used to explore the structure and phase of the compound. On the basis of the Archimedes principle, the density of crystals was estimated to be 5.442 kg mm À3 . The resistivity and conductivity type were determined by the van der Pauw method. UV-vis-NIR studies revealed a direct transition with an energy gap of 1.69 eV. Mechanical properties such as microhardness, toughness, Young's modulus and elastic stiffness constant of GaTe crystals in response to the stress field due to an external load were studied to realize their suitability for radiation detector applications. The present observations provide an insight into the physical properties of the vapour-grown GaTe platelets, which are found to be superior over their melt counterparts.

Grain-growth engineering and mechanical properties of physical-vapour-deposited InSe platelets

“…The latter shows successive stages of phase transformation from vapour to solid. The initiation of the solid phase occurs when individual nuclei coalesce into larger clusters by aggregation, which strongly controls the formation and growth of new nuclei (Pamplin, 1975;Kunjomana et al, 2014). In the present work, heterogeneous nucleation was induced by the adsorption of atoms on perfectly clean ampoule walls, free from foreign impurities to eliminate branching of crystallites.…”

“…The non-equilibrium state was thus established by fostering particle diffusion towards the growth zone. Stable growth was experimentally promoted by optimizing the chemical potential in terms of the concentration gradient which arises from the difference in temperature, ÁT = T C À T S , such that stoichiometric InSe platelet crystals were deposited, as explained by Kunjomana et al (2014).…”

“…1(a). For the experimental trials, about 3.330 g of the prepared charge (total mass of InSe = 10 g) was powdered and loaded into an ampoule, high-vacuum sealed ($10 À6 mbar) and kept in an in-house-fabricated horizontal dual-zone furnace with a temperature controlling mechanism, as discussed by Kunjomana et al (2014). The basis of all vapour growth experiments may be described by a simplified model, which postulates that atoms (or molecules) from the vapour phase that impinge on the surface of a substrate are adsorbed to form a crystal.…”

Studies on sulfur doping and figure of merit in vapor grown Sb2Te3 platelet crystals

“…Due to this anisotropic bonding environment and supersaturation, the rate of crystal growth is greater along the basal (0001) planes than along the c-axis, resulting in the form of plate-like habits. With appropriate temperature gradient, the transport of the vapor of the charge material is enhanced and is supersaturated so as to favor the platelet morphology as reported by Kunjomana et al [12]. Under the effect of enhanced super saturation, platelets occur lying in the basal plane, thus conforming to the crystal symmetry [15].…”

“…Using Vicker's diamond pyramidal indenter, microhardness studies have been carried out for loads varying from 5 to 100 g, for an indentation time of 10 s as described by Kunjomana et al [12].…”