Keywords

MoS₂ nanomechanical resonators

Subject Categories

Electrical and Computer Engineering | Mechanical Engineering

Abstract

Two-dimensional (2D) materials have emerged as promising candidates for nanoelectromechanical systems (NEMS) due to their exceptional mechanical, optical, and electrical properties. Among these materials, molybdenum disulfide (MoS2) has attracted considerable interest for nanomechanical resonator applications because of its low mass density, high mechanical strength, and semiconducting nature. This thesis presents the fabrication, theoretical modeling, and experimental characterization of suspended MoS2 drumhead resonators. The devices were fabricated by mechanically exfoliating MoS2 flakes from bulk MoS2 crystals and transferring selected flakes onto pre-patterned substrates using a dry-transfer process. Mechanical resonance was excited through photothermal actuation using a modulated blue laser, while device motion was detected using optical interferometric readout with a red probe laser. The optical properties of the multilayer Air/MoS2/Air/Pt/Ti/Sapphire structure were analyzed using a multilayer interference model to determine reflectance, transmittance, optical absorption, and interferometric responsivity. Thermal modeling was performed to evaluate the thermal cutoff frequency, temperature distribution, and thermally induced strain generated during optical excitation. For the fabricated device geometry, the optical absorption was calculated to be approximately 52%, the thermal cutoff frequency was estimated to be 144.17 kHz, and the center temperature under optical excitation was predicted to be approximately 304.5 K. Experimental measurements demonstrated successful photothermal excitation of the suspended MoS2 resonator, yielding a resonance frequency from 31.7 MHz to 49.1 MHz with a quality factor ranging from approximately 24 to 95.1 under ambient conditions. The experimental observations showed good agreement with the theoretical optical and thermal models. The results demonstrate the feasibility of photothermally excited MoS2 nanomechanical resonators and provide insight into the coupled optical, thermal, and mechanical processes governing their operation.

Completion Date

2026

Semester

Summer

Committee Chair

Lee, Jaesung

Degree

Master of Science in Electrical Engineering (M.S.E.E.)

College

College of Engineering and Computer Science

Department

Electrical Engineering

Format

PDF

Document Type

Thesis

Language

English

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