GeSn/SiGeSn Heterostructure and MQW Lasers: towards high efficiency
Student: Solomon Ojo
Degree: M.S., May 2020
Major Professor: Dr. Fisher Yu
High-performance silicon-based lasers and detectors are sought after, owing to the possibility of monolithic integration of photonics with high-speed Si electronics.
GeSn/SiGeSn offer design options from bulk to heterostructure and quantum wells useful for the fabrication of a group IV laser.
Bandgap engineering for efficient light emission with wide range of wavelength coverage from near to Long-wave infrared.
Explore novel growth techniques to reduce defects and gain access to compositions never grown before; high quality and stable (Si)GeSn alloys with high Sn content.
- Epitaxial growth of high Sn composition of GeSn and SiGeSn using PEUHV-CVD.
- LED and laser devices fabrication.
- Investigate (Si)GeSn electrical and optical properties using Fourier-transform infrared spectroscopy (FTIR).
- Investigate structural parameters by transmission electron microscopy (TEM) and high resolution X-ray diffraction (HRXRD).
- Temperature-dependent PL spectroscopy in a cooled closed-cycle cryostat.
- Improved optically pumped GeSn lasers with high operating temperature towards RT.
- Higher Sn incorporation with optimization of parameters for Plasma Enhancement technique
- Enhanced radiative recombination due to the localization of electrons and holes in quantum wells.
- Lasing up to near room temperature, 270 K, which could be attributed to high material quality.
- Improved carrier confinement by increasing well width, elevating Sn composition in the GeSn buffer layer, and using SiGeSn as barrier.
- Development of a systematic method to explore the optimal growth condition to achieve higher quality and higher Sn composition.
MQW development for future devices such as lasers, LED, and photodetector should be further investigated.