Development of ErAs-embedded III-V semiconductor structures for terahertz photoconductive devices

Abstract

Terahertz (THz) technology has emerged as a promising platform for applications in spectroscopy, imaging, and high-speed communications. However, the development of compact, efficient, and telecom-compatible THz sources and detectors remains a significant challenge. To address this challenge, this dissertation focuses on the growth, fabrication, and characterization of ErAs-embedded III-V semiconductor heterostructures for photoconductive antennas (PCAs) designed to operate under 1550 nm optical excitation. ☐ Molecular beam epitaxy (MBE) was employed to synthesize ErAs:GaAs and digital alloys of [ErAs:(InGaBiAs)x(InAlBiAs)1−x], with precise control of fluxes and growth temperature to optimize bulk resistivity, carrier lifetime, and bandgap compatibility with telecom wavelengths. The structural, optical, and electrical properties of the films were characterized using high-resolution X-ray diffraction (HRXRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), spectrophotometry, Hall effect measurements, and optical pump THz probe spectroscopy (OPTHzP). ☐ Devices were fabricated using maskless laser photolithography and lift-off metallization techniques. A PCA detector of THz based on ErAs:InGaAlBiAs demonstrated measurable response at 1550 nm excitation, while ErAs:GaAs was integrated with a spintronic emitter architecture to explore THz pulse shaping and chirality control. Functional testing using THz time-domain spectroscopy (THz-TDS) was used to evaluate device performance. ☐ Overall, this work establishes a fabrication and characterization approach for ErAs-based THz PCAs and highlights the potential of digital alloy heterostructures for applications requiring compatibility with telecom-band excitation.