Author ORCID Identifier:
Date of Graduation
7-2026
Document Type
Dissertation
Degree Name
Doctor of Philosophy in Materials Science & Engineering (PhD)
Degree Level
Graduate
Department
Materials Science & Engineering
Advisor/Mentor
Yu, Shui-Qing (Fisher)
Committee Member
Hu, Jin
Second Committee Member
Churchill, Hugh
Third Committee Member
Kohanek, Julia
Fourth Committee Member
Du, Wei
Keywords
SiGeSn-Based Lasers, Silicon, Mid-Infrared Optoelectronics, Dual-Barrier SiGeSn/GeSn
Abstract
Germanium-tin (GeSn) alloys represent a significant advancement in semiconductor technology, particularly for applications in the short-wave and mid-infrared (SWIR and MIR) spectral ranges. As a group IV material system, these alloys offer a unique combination of tunable optoelectronic properties and full compatibility with established silicon-based manufacturing processes. The controlled incorporation of tin into germanium enables the engineering of a fundamental direct bandgap, a critical feature that distinguishes GeSn from its indirect bandgap materials, silicon and germanium. This direct bandgap behavior which was demonstrated in high-quality single crystalline GeSn alloys around the year 2015 is the foundation for efficient light emission and absorption at extended wavelengths. The potential of this material system extends beyond photonic devices to high-performance electronic components. The higher carrier mobilities and increased band-to-band tunneling properties of direct bandgap GeSn are of high importance for developing next-generation transistors such as high-speed field-effect transistors (FETs) and low power tunnel FETs. Similarly, the GeSn alloys have assured the research community to enable a new class of integrated devices that combine photonic and electronic functionalities on a single chip. This monolithic integration is a vital step towards overcoming the limitations of conventional electronics by assisting the parallel optical data transmission with minimal power consumption. However, the novelty of the GeSn material system also presents substantial challenges. The development of practical devices requires the optimization of all foundational processing steps starting from epitaxial growth and defect analysis to doping strategies, device fabrication and testing. Research into these areas is crucial since the presence of defects near active regions can severely degrade optical performance. Investigations of spontaneous and stimulated emission by photoluminescence and electroluminescence characterization have provided critical insights into the behavior of this material including the effects of strain relaxation and temperature-dependent non-radiative recombination. This dissertation details groundbreaking work in the development of optically pumped and electrically injected GeSn lasers including Novel design and demonstration of a dual-barrier heterostructure (SCH) for optically pumped laser for the first time for group-IV semiconductor materials to advance the study and application of this novel material system. Here I present the different efforts in the process of development of GeSn Laser starting from the material growth and optimization, optical setup upgrade and optimization, Electrically injected laser characterization and pointing out and proposing the solution for the major factor limiting the performance of current GeSn laser to adopting the Dual-Barrier SiGeSn/GeSn for demonstrating Optically Pumped laser . Finally, I have also shown the path towards SAG technique, adopted in III-V materials a long time before, for material growth of SiGeSn material. The optically pumped lasing temperature of 235 K was achieved by incorporating the 18% Sn in the bulk active region. In our previous work, a dual-barrier design (SiGeSn barrier/GeSn barrier/GeSn well) exhibited improved carrier collection efficiency for a GeSn single QW structure compared with a single-barrier configuration; However, no lasing had been reported from single QW devices to date. Here, we report lasing from a GeSn dual-barrier single QW structure up to 140 K, with a threshold of 67 kW/cm2 at 77 K, representing a substantial threshold reduction. Lasing from the single-QW device is attributed to high material quality, improved carrier collection efficiency, and suppressed Auger recombination resulting from the lower carrier density. Similarly exploring paradigm-shifting approaches like ART to break away from traditional limitations has been introduced in this dissertation.
Citation
Acharya, S. (2026). SiGeSn-Based Lasers on Silicon for Mid-Infrared Optoelectronics. Graduate Theses and Dissertations Retrieved from https://scholarworks.uark.edu/etd/6317
