Optical Characterization of GeSn Thin Films

Student: Eleni Becton

Major Professor: Dr. Fisher Yu

Research Area(s):

Microelectronics

Group III-V Semiconductors are currently used for Si Photonics but aren’t suitable for industry due to their high cost, and incompatibility with CMOS processes.
Group IV Semiconductor Ge is considered as a pseudo-direct bandgap material, because the difference between the direct and indirect bandgap of Ge is only 0.140 meV.
Since the difference between the direct and indirect bandgap is small, the bandgap can be modified to eventually achieve a direct bandgap Ge.

Fabrication of cost effective and high-efficient Si-based emitters that can cover the short-wave and mid-infrared range of spectrum for Si photonics and optoelectronic industry.

Alloying GeSn as opposed to strain or heavily n-doping deals with wavelength limitations.
Testing GeSn alloy for temperature and excitation power using temperature dependent photoluminescence.
Increasing Sn composition x> 9%, results in decreased bandgap material to GeSn alloy providing a direct bandgap GeSn material through temperature testing ranging from 10-300K.

High quality GeSn thin films were grown using commercial CVD machine
Temperature dependent and power dependent PL was performed on 9% GeSn sample
PL intensity in low temperature was significantly higher than the room temperature intensity

GeSn thin films can be grown monolithically on Si or Ge buffer in an inexpensive way compared to group III-V semiconductors
GeSn grown on Si has a capability to be applied in the future of Si Photonics technology
High Sn composition GeSn samples with higher thickness presents a direct bandgap material for the future of infrared light emitting devices and lasers