ORCID

0000-0002-5784-412X

Keywords

Thermoelectric radiation detectors, Antenna-coupled devices, Bi₂Te₃–Sb₂Te₃ thin films, Millimeter-wave sensing, Room-temperature detection, RF sputtering and annealing

Abstract

We explore the development of antenna-coupled thermoelectric detectors for long-wavelength radiation using sputtered bismuth telluride (Bi2Te3) and antimony telluride (Sb2Te3) thin films. Detection in the infrared, millimeter-wave, and terahertz regimes is critical for sensing, imaging, and energy applications; however, many existing detectors rely on cryogenic operation, exhibit narrow spectral response, or require complex material systems. In this work, we investigate the feasibility of reliable, room-temperature long-wavelength detection using microfabricated thermoelectric thin films integrated with antenna structures. A systematic full-factorial experimental approach was employed to determine how sputtering parameters and post-deposition annealing influence the structural, electrical, and thermoelectric properties of Bi2Te3 and Sb2Te3 films. The results show that the Seebeck coefficient of sputtered Sb2Te3 is largely insensitive to processing variations, whereas film thickness and transport properties are strongly governed by deposition conditions and thermal treatment. Annealing improves crystallinity, increases grain size, and reduces resistivity, indicating enhanced electrical connectivity within the films. A key finding of this work is the identification of oxidation behavior in Sb2Te3 thin films. Far-infrared spectroscopy, supported by structural characterization and secondary ion mass spectrometry (SIMS) depth profiling, reveals that Sb--O vibrational features originate primarily from a thin buried layer at the film-substrate interface rather than from bulk oxidation. This interfacial oxidation evolves with annealing while transport properties improve, highlighting a complex relationship among microstructure, chemistry, and device performance. Optimized Bi2Te3 and Sb2Te3 films were subsequently integrated into bowtie antenna-coupled thermoelectric detectors fabricated using photolithographic processing. Electrical and photoresponse measurements demonstrate broadband, room-temperature operation from infrared to millimeter-wave frequencies, along with polarization dependence consistent with antenna coupling and distinct response mechanisms across spectral regimes. Together, these results establish a fabrication-tolerant framework for thermoelectric thin-film processing, elucidate the role of annealing-induced interfacial oxidation, and demonstrate the feasibility of antenna-integrated thermoelectric detectors for broadband long-wavelength detection.

Completion Date

2026

Semester

Spring

Committee Chair

Peale, Robert

Degree

Doctor of Philosophy (Ph.D.)

College

College of Sciences

Department

Physics

Format

PDF

Document Type

Dissertation

Identifier

DP0053139

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