The Effects of Ge Substrate Surface States and Au Catalyst Layer Thickness on the Growth of Different Ge<sub>x</sub>O<sub>y</sub> Nanomaterials and Nanocrystals Configurations Using Vapor-Liquid-Solid Method with two Steps Temperature Mode

Abstract

Recently the Ge<sub>x</sub>O<sub>y</sub> nanomaterials have been studied intensively due to their interesting electronic materials, which have many particular properties and applications in nanotechnology and nano-devices fabrication. Much work has been done on many different synthesis methods and their properties of Ge and Ge<sub>x</sub>O<sub>y</sub> nanomaterials. However, the effects of the different Ge substrate surface states and Au catalyst layer thicknesses on the formation of different forms/morphologies of nanomaterials (nanowires, nanorods, nanoparticles, and nanocrystals particularly) have yet to be discussed more in detail. This paper outlines the synthesis methods to grow the different Ge<sub>x</sub>O<sub>y</sub> nanomaterials on the different Ge surface states at different Au catalyst layer thicknesses such as mechanically polished surface, deep Chemical etched surface, chemical polishing surface, and initial rough surface. The morphological, and structural properties of Ge<sub>x</sub>O<sub>y</sub> nanomaterials have been investigated using SEM, EDX, and TEM techniques. The formation of different morphological, and structural properties of different Ge<sub>x</sub>O<sub>y</sub> nanomaterials grown have been explained by the effects of the Au/Ge/O droplets/clusters formation situations and surface defects on the Ge substrate surface caused. The growth mechanisms have been explained by the model of the VLS growth method with the Oxide Assist Growth mechanism. The results showed that the effects of the different Ge substrate surface states and Au catalyst layers’ thickness strongly influence the formation of Ge<sub>x</sub>O<sub>y</sub> materials in terms of the sizes, structures, and percentages of elements. The results of the controllable different Ge<sub>x</sub>O<sub>y</sub> nanomaterials have many significant meanings for both theoretical and practical applications in nanomaterials and nano-device fabrication.