Date of Graduation
8-2017
Document Type
Dissertation
Degree Name
Doctor of Philosophy in Microelectronics-Photonics (PhD)
Degree Level
Graduate
Department
Microelectronics-Photonics
Advisor/Mentor
Shui-Qing Yu
Committee Member
Gregory J. Salamo
Second Committee Member
Simon Ang
Third Committee Member
Hameed A. Naseem
Fourth Committee Member
Rick Wise
Keywords
GeSn, Lasers, Optoelectronics, Photonics, Semiconductor
Abstract
Silicon-based materials and optoelectronic devices are of great interest as they could be monolithically integrated in the current Si complementary metal-oxide-semiconductor (CMOS) processes. The integration of optoelectronic components on the CMOS platform has long been limited due to the unavailability of Si-based laser sources. A Si-based monolithic laser is highly desirable for full integration of Si photonics chip. In this work, Si-based germanium-tin (GeSn) lasers have been demonstrated as direct bandgap group-IV laser sources. This opens a completely new avenue from the traditional III-V integration approach. In this work, the material and optical properties of GeSn alloys were comprehensively studied. The GeSn films were grown on Ge-buffered Si substrates in a reduced pressure chemical vapor deposition system with low-cost SnCl4 and GeH4 precursors. A systematic study was done for thin GeSn films (thickness < 200 nm) with Sn compositions from 0 to 12%, and for thick GeSn films (thickness > 400 nm) with Sn composition 5 to 17.5%. The room temperature photoluminescence (PL) spectra were measured that showed a gradual shift of emission peaks towards longer wavelength as Sn composition increases. Strong PL intensity and low defect density indicated high material quality. Moreover, the PL study of n-doped samples showed bandgap narrowing compared to the unintentionally p-doped (boron) thin films with similar Sn compositions. Finally, optically pumped GeSn lasers on Si with broad wavelength coverage from 2 to 3 μm were demonstrated using high-quality GeSn films with Sn compositions up to 17.5%. The achieved maximum Sn composition of 17.5% broke the acknowledged Sn incorporation limit using similar deposition chemistry. The highest lasing temperature was measured at 180 K with an active layer thickness as thin as 270 nm. The unprecedented lasing performance is due to the achievement of high material quality and a robust fabrication process. The results reported in this work show a major advancement towards Si-based electrically pumped mid-infrared laser sources for integrated photonics.
Citation
Al-Kabi, S. H. (2017). Si-Based Germanium Tin Semiconductor Lasers for Optoelectronic Applications. Graduate Theses and Dissertations Retrieved from https://scholarworks.uark.edu/etd/2505
Included in
Electromagnetics and Photonics Commons, Electronic Devices and Semiconductor Manufacturing Commons