Growth of polycrystalline Si0.7Ge0.3 on various substrates for thermoelectric applications
Journal
Journal of Crystal Growth
Journal Volume
585
Date Issued
2022
Author(s)
Abstract
Silicon germanium has been known to be one of the best thermoelectric materials for high temperature applications but has yielded mediocre efficiency values. The thermoelectric efficiency is inversely proportional to thermal conductivity, which decreases with increasing grain boundaries. To maximize the grain boundaries or decreasing grain size during crystal growth, this work aimed to observe in-situ the growth behavior of Si0.7Ge0.3 on various substrates, including SiC, Si3N4, and Si3N4:Si substrates at cooling rates of 5, 20, and 100 K/min. Sample undercooling was found to have no significant temperature dependence on SiC and Si3N4:Si with average values of 0.6 K and 1.9 K, respectively. Crystal growth behaviors were found to be dependent on the cooling rate, undercooling, and substrate materials. Higher cooling rates generated more grains and SiC was found to generate the most with the smallest portion of segregated melts, while Si3N4 was found to be the opposite. Growth behaviors were further confirmed through scanning electron microscope analyses of samples. © 2022 Elsevier B.V.
Subjects
A1. Dendrites; A1. Nucleation; A1. Solidification; A1. Substrates; B1. Germanium silicon alloys; B3. Infrared devices
SDGs
Other Subjects
Cooling; Efficiency; Grain boundaries; Grain growth; High temperature applications; Polycrystalline materials; Scanning electron microscopy; Semiconductor alloys; Si-Ge alloys; Silicon carbide; Temperature distribution; Thermal conductivity; Thermoelectric equipment; Thermoelectricity; A1.; B1.; B3.; Dendrite; Grain-boundaries; Growth behavior; Various substrates; Substrates
Type
journal article