A Study of the Structural, Optical, and Ferroelectric Characteristics of Pb-Ge-Te Nanocrystalline Alloys As Potential Candidates for Memory Devices and Near-Infrared (NIR) Applications

Pb50-xGexTe50 (x = 15, 20, 25, 30 at. %) nanocrystalline bulk alloys were prepared using solid-state direct reaction. X-ray diffraction and high-resolution transmission electron microscopy (HR-TEM) analysis of the reference structure (Ge = 15 at.%) revealed a slightly distorted cubic structure, with a lattice parameter of 6.43 angstrom and an inter-axis unit cell angle of 88.69 degrees. Atomic force images' analysis and histograms displayed a homogenous particle size distribution in the nanoscale for all samples. Density measurements showed a gradual decrease from 7.89 to 6.98 g/cm(3) with increasing Ge content in agreement with the calculated values. The polarization-field hysteresis behavior verifies the ferroelectric activity of the prepared alloys, suggesting them as potential candidates for non-volatile ferroelectric memory devices (NVFRAMs) applications. Optical properties analyzed using diffuse reflectance measurements exhibited direct transitions with a bandgap decreasing from 1.57 to 1.35 eV with increasing Ge content matching the near-infrared spectrum (NIR) perfectly.