Researcher(s)
- Gwen DelJones, Material Science, Rutgers University-New Brunswick
Faculty Mentor(s)
- Joshua Zide, Materials Science and Engineering, University of Delaware
Abstract
The region between microwaves and infrared light on the electromagnetic spectrum, known as the terahertz gap, possesses the potential to improve analytical techniques in fields such as medical imaging and quality control. However, few accessible methods and materials are available to control Terahertz radiation. Materials grown by MBE are fabricated into a photoconductive switch (PCS) to interact with these signals. A multicolor THz emitter is proposed for innovation in THz emission and pulse control [1]. This device will require more complex fabrication techniques such as dry etching. Bismuth and Erbium have been incorporated into the III-V semiconductor InAlAs for improved terahertz capabilities, although these additions may cause complications in processing [2]. For continued innovation, it is necessary to revise the etch design to include a secondary PCA and investigate the existence of a characteristic etch rate for these novel materials. Photolithography techniques apply a mock etch design to 0.8×0.8 cm samples of material using photoresist and a laser writer. Then, samples undergo chlorine inductively coupled plasma (Cl-ICP) etching for various lengths of time. Etch depth was measured by profilometry and the sample surface was observed with optical microscopy. To proceed with experimentation, it was imperative to establish a foundational recipe for Cl-ICP etching InAlAs [3]. The gas flow rate ratio of BCl3 and N2 appeared to affect the ignition of gas for etching. A 1:2 ratio was unpredictable, leading to the damage of an InAlAs sample after adjusting the system’s power. InAlBiAs and ErAs:InAlBiAs samples endured a 2:1 ratio with a consistent, but aggressive etch, penetrating the substrate and destroying ErAs:InAlBiAs samples. Future studies will focus on optimizing system parameters and substituting the process for a wet technique.
Works Cited
[1] W. Wu, W. Acuna, Z. Huang, X. Wang, L. Gundlach, M. F. Doty, J. M. O. Zide, M. B. Jungfleisch, Hybrid Terahertz Emitter for Pulse Shaping and Chirality Control. Adv. Optical Mater. 2025, 13, 2402374. https://doi.org/10.1002/adom.202402374
[2] W. Acuna, W. Wu, J. Bork, M. F. Doty, M. B. Jungfleisch, L. Gundlach, J. M. O. Zide, Band Engineering of ErAs:InGaAlBiAs Nanocomposite Materials for Terahertz Photoconductive Switches Pumped at 1550 nm. Adv. Funct. Mater. 2024, 34, 2401853. https://doi.org/10.1002/adfm.202401853
[3] T. Maeda et al., “Inductively coupled plasma etching of III–V semiconductors in BCl3-based chemistries: II. InP, InGaAs, InGaAsP, InAs and AlInAs,” vol. 143, no. 1, pp. 183–190, 1999, doi: 10.1016/S0169-4332(98)00593-5.