Metal Assisted Chemical Etching for Quantum Cascade Lasers

Student’s name: Ameya Matele Home Institution: The University of Texas at Austin NNCI Site: MRC @ The University of Texas at Austin REU Principal Investigator: David Burghoff REU Mentor: Zheheng Xu Abstract: Quantum Cascade Lasers (QCLs) are semiconductor lasers operating in the mid to long infrared and terahertz regimes. These lasers are composed of multiple quantum wells that create a superlattice structure. As electrons pass through these wells, they transition between energy levels and emit photons at each step. This cascade effect allows a single electron to generate multiple photons, enhancing efficiency. Compared to other lasers, it has broad tunability, robustness, and compactness. QCLs provide a faster and more precise alternative to FTIR, mass spectrometry, and photothermal microspectroscopy, particularly in high-resolution spectroscopy and real-time gas analysis. However, most QCLs fabrication techniques rely on wet or dry etching, such as ICP-RIE (Inductively Coupled Plasma Reactive Ion Etching), both of which introduced artifacts that degrade performance. Metal-Assisted Chemical Etching (MacEtch) is a technique that uses the catalytic properties of metals to enhance the wet etching process, producing anisotropic high aspect ratio structures, damage-free sidewalls, and efficient patterning of semiconductors at the micro and nanoscale. In this project, we will demonstrate a high-performance GaAs/AlGaAs-based QCLs by using the MacEtch process. We will also explore different etching and patterning recipes to optimize the GaAs/AlGaAs MacEtch technique. This research aims to offer an alternate fabrication process for QCLs, ultimately improving their performance and application range.