Amorphous and Crystalline GeTe Nanocrystals

A facile method for the synthesis of crystalline and amorphous GeTe nanoparticles (NPs) using bis((trimethylsilyl)amido)germanium(II), Ge[N(SiMe3)(2)](2), and elemental tellurium dispersed in tri-n-octylphosphine (TOP) is reported. As synthesized, crystalline particles exhibit narrow dispersity at smaller sizes and tend to grow into anisotropic shapes with increasing reaction time (growth). Furthermore, crystalline GeTe NPs possess rhombohedral symmetry with absorption band energies in near IR region (0.76-0.86 eV). Amorphous GeTe particles prepared at low temperatures are nearly spherical in morphology and display amorphous-to-crystalline phase transition at 209-237 degrees C depending on their primary particle size. Detailed investigation of the local structure of the amorphous GeTe using pair distribution function (PDF) method reveals that it is closely related to that of the pressure- and temperature-stabilized orthorhombic GeTe.