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

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. 


Strain induction on GE nanobeams by electrostatic actuation
Ayan, Arman; Yerci, Selçuk; Department of Electrical and Electronics Engineering (2018)
Germanium (Ge) is one of the most promising materials to accomplish the monolithic integration of optics and electronics on the same chip, mainly due to its compatibility with the existing silicon (Si) technology, high charge carrier mobility and high absorption coefficient in the near-infrared region. However, realization of efficient Ge light emitters requires techniques such as tensile strain induction, tin (Sn) incorporation and/or heavy n-type doping to alter its band gap enabling direct transitions. A...
Design and fabrication of strained light emitting germanium microstructures by liquid phase epitaxy
Ünlü, Buse; Yerci, Selçuk; Boztuğ Yerci, Çiçek; Department of Micro and Nanotechnology (2021-9)
Germanium is compatible with CMOS technology and can be utilized for the development of an integrated laser on Si platforms. Nevertheless, it is a very inefficient light emitter owning to its indirect bandgap. On the other hand, the application of tensile strain reduces the split in between direct and indirect band edges of Ge, which in turn enhances its light emission efficiency, and converts it into a direct bandgap material. In this thesis, firstly finite element model simulations are performed to determ...
Modification of TiO2 and NiO charge selective mesoporous layers using excessive Y and Li additions for carbon based perovskite solar cells
Icli, Kerem Cagatay; Özenbaş, Ahmet Macit (2021-09-15)
Carbon based perovskite solar cells are rapidly emerging as promising photovoltaic devices, combining low cost production and prolonged device operation, due to the exclusion of polymeric conductors and integration of highly durable metal oxide charge selective layers. Modification of metal oxide mesoporous layers via element additions and enhancement of electrical conductivity is a major strategy for reduced internal resistances inside the cell. This work investigates the effect of excessive Y and Li addit...
Improvement of light emission from Tb-doped Si-based MOS-LED using excess Si in the oxide layer
Kulakci, Mustafa; Turan, Raşit (2013-05-01)
The fabrication of efficient silicon-based Light Emitting Devices (LEDs) is extremely important for the integration of photonic and electronic components on the same Si platform. In this paper, we report on the room temperature electroluminescence properties of Tb-doped MOS-LED devices with an active layer of SiO2 and Si-rich SiOx produced using the magnetron co-sputtering technique. The electroluminescence properties of both types of devices were studied as a function of processing conditions and material ...
Characterization of Multilayered Conductive Films Produced by Multiple Transfer Printing Graphene onto Ultra-Thin PVC Foil
Inkaya, Uğur; Çelik, Kübra; Oral, Ahmet (null; 2017-11-30)
Having high charge carrier mobility and superior elastic properties, graphene is a very suitable material for flexible electronics. However, it is usually desired to remove and prevent unintentional doping due to wet processes used for transfer printing of graphene. Although it does not produce a graphene film as smooth as an exfoliated graphene sheet transferred onto SiO2/Si wafer, dry transfer of graphene could be favored for applications that do not require very high charge carrier mobility. In addition,...
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.