Abstract
Germanium-Tin (GeSn) semiconductor alloy has been considered as a candidate for implementing active Group IV optoelectronics. In this thesis, a Ge1-xSnx metal-semiconductor-metal (MSM) photodetector fabricated on Si substrate by rapid melt growth method with graded Sn concentration up to 5-10 %, which is higher than the solid solubility (~ 1 %) of Sn in Ge is demonstrated. The crystal orientation and elemental composition of the GeSn alloy are characterized by selected area diffraction (SAD) pattern and energy dispersion spectroscopy (EDS), showing a monocrystalline semiconductor quality and Sn concentration profile. This crystal quality of GeSn alloy is also investigated by Raman spectroscopy. Finally, we measure the photocurrent of the device and verify the GeSn MSM photodetector has a mid-IR photoresponse at wavelength of 2 μm.