| Group IV based devices are widely used in the electronic device industry especially Silicon-Germanium (SiGe) alloys. The possibility of optoelectronic devices based on Group IV materials is especially very attractive due to the compatibility of integration with the current Si-based CMOS processing technology.;In this work SiGe and GeSn alloys were grown on Si and Ge (100) substrates using molecular beam epitaxy (MBE). The growth stages in SiGe alloys were studied with varying thicknesses and composition of the alloys, and it was found that the defect density depended on the rate of growth and the initial elastic strain.;Germanium-Tin (GeSn) alloys are technologically important for group IV based optoelectronic devices due to the possible transformation of the bandgap from indirect to direct in k-space. It has been shown; however, that epitaxial growth of GeSn alloys can lead to Sn segregation. In this work high crystalline quality GeSn alloys, with relatively high Sn composition, were grown on Ge (0 0 1) substrates using MBE. The growth conditions, lattice constant dependence on Sn composition and the thermal stability of the Ge1-xSn x alloys were investigated.;In recent years, Magnetic tunnel junction (MTJ) based sensors have been used for bio-detection applications. In this work, Al2O3- and MgO-based MTJ sensors were designed and fabricated using microfabrication techniques such as UV photolithography, ion-beam etching, etc. on an oxidized silicon substrate. The effect of shape anisotropy on the TMR of the sensors was investigated along with the detection of nanoparticles.;The results of this research on the growth, fabrication and structural characterization of SiGe and GeSn alloys, and MTJ based biosensors are useful for Group IV based optoelectronic devices such as photoconductors, LEDs, which can be monolithically integrated with the current Si-based CMOS processing, and biosensors which can detect biomolecules attached to magnetic nanoparticles. |
