ORCID

0000000241637740

Keywords

Quantum Cascade Lasers, semiconductor lasers, electron microscopy, modeling, failure analysis

Abstract

As advancements in Quantum Cascade Laser (QCL) technology continue to push the upper limits of continuous-wave performance, effective thermal management remains at the forefront of design considerations. The compact and highly tunable active region that has made QCL technology so attractive also imposes challenges to heat dissipation during continuous wave operation. To address this ongoing challenge, this work demonstrates a set of characterization and modeling techniques which can be used to interrogate different aspects of the thermal and structural properties of QCLs. Emphasis is placed on a suite of electron microscopy techniques and their role in providing a window into large and nanoscale defects in QCLs, both pre-existing and operationally induced.

One investigation combines advanced spectroscopy with thermal modeling to directly measure the active region temperature during CW operation and determine the cross-plane thermal conductivities of different QCL designs, providing insights into how such design considerations ultimately influence QCL performance. Cathodoluminescence imaging is then demonstrated as a nondestructive approach to epitaxial material quality assessment in QCLs grown on different substrates. Another study characterizes the degradation of long wave Buried Heterostructure QCLs through electron microscopy, successfully identifying the origins of failure and providing insights into the mechanisms that cause it. Finally, this methodology is refined in a comparative electron microscopy analysis of Ridge-Waveguide QCLs, which also introduces Cathodoluminescence Imaging to further characterize the origin and propagation of defects. Collectively, these studies provide effective tools for QCL characterization, while also providing insights into the specific mechanisms of failure in a subset of devices. This work ultimately aims to contribute to guiding future QCL design strategies for improving the reliability and performance of these devices.

Completion Date

2025

Semester

Summer

Committee Chair

Arkadiy Lyakh

Degree

Doctor of Philosophy (Ph.D.)

College

College of Optics and Photonics

Department

Optics and Photonics

Format

PDF

Identifier

DP0029625

Language

English

Document Type

Thesis

Campus Location

Orlando (Main) Campus

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