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Comparison of Poole-Frenkel and Hartke Emission Currents in a Capacitive Micromachined Ultrasonic Transducer (CMUT)

Authors:
Chukwuebuka Okoro
Sazzadur Chowdhury

Keywords: Quantum Tunneling; Current Density; Hartke; Poole-Frenkel; CMUT; Dielectric Charging.

Abstract:
This study investigates the Poole-Frenkel and 3D Hartke models of electron emission from trap centers in silicon nitride membranes in Capacitive Micromachined Ultrasonic Transducers (CMUTs). The study compared the trap-emitted electron current densities calculated using both models for a CMUT, with a 0.5 micrometer thick silicon nitride structural layer suspended over a 600 nanometer thick vacuum gap. The comparison results demonstrate that the Poole-Frenkel model consistently predicts electronic current densities that exceed the Hartke model predictions by more than 99% for a DC bias voltage range of 11-77 volts. This significant variation in predicted current densities is primarily due to the inclusion of multi-directional emission paths in the Hartke model. In contrast, the Poole-Frenkel model considers emissions only in one direction. The study provides valuable insights into the dielectric charging mechanisms in CMUTs, which can aid in the development of solutions to enhance their reliability.

Pages: 10 to 14

Copyright: Copyright (c) IARIA, 2025

Publication date: October 26, 2025

Published in: conference

ISSN: 2308-3514

ISBN: 978-1-68558-305-7

Location: Barcelona, Spain

Dates: from October 26, 2025 to October 30, 2025