Single Phase Metastable Alloys by PLD-Layering

Pulsed laser deposition (PLD) is a high-energy synthesis technique that enables novel thin film systems with versatile and interesting chemistry. An example is the metastable heterostructural alloy Sn1-xCaxSe, an alloy of cubic rocksalt CaSe and orthorhombic SnSe, which is predicted to transition from RS to OR at x $=$ 0.13. In PLD, high energy species overcome high mixing enthalpies to form metastable structures. If decomposition pathways are kinetically hindered, an alloy is stabilized. Here we explore how PLD can form stable, single-phase alloys with different microstructures and properties. Structural properties of all compositions were examined by TEM, STEM, and electron and x-ray diffraction; composition by electron probe microanalysis and energy dispersive x-ray spectroscopy. Seebeck and Hall coefficients were measured to quantify the thermal and electrical properties and optical transmission and reflection determined the band gap and absorption.