Development of a large area germanium on insulator platform by liquid phase epitaxy

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2017
Özyurt, Zişan İrem
Germanium is a group IV element compatible with CMOS (Complementary metal oxide semiconductor) fabrication technology and advantageous over silicon by having smaller band gap and higher carrier mobility, which provide infrared photodetectors and high-speed transistors respectively. In addition, by having direct band gap, strained-Ge enables fabrication of infrared lasers. Finally, thanks to lattice-matching, Ge layers on Si can also be used as virtual substrates for the growth of III-V compounds on Si. In order to enable these technological developments, single crystalline Ge (c-Ge) needs to be grown on a low cost CMOS material, preferably Si. Within this scope, Ge films were grown on SiO2 layers using liquid phase epitaxy enabled by crystalline Si (c-Si) seed window and rapid melting method. Effects of insulator, Ge film and capping layer thicknesses, temperature and cooling rate were probed by electron backscatter diffraction (EBSD) and Raman measurements. We demonstrated that while insulator thickness decreases the crystal quality, Ge film and capping layer thicknesses typically have a positive effect on crystal structure. Additionally, we observed that there is an optimum temperature around the melting point of Ge. Finally, we showed that lower cooling rates contributes to single crystal formation. The results of this research can offer a material platform for fabrication of infrared photodetectors, high-speed transistors and infrared lasers as well as low-cost high-efficiency solar cells providing economic and industrial benefits for photovoltaics. 

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Citation Formats
Z. İ. Özyurt, “Development of a large area germanium on insulator platform by liquid phase epitaxy,” M.S. - Master of Science, Middle East Technical University, 2017.