Performance Analysis of Scandium-Doped Aluminum Nitride-Based PMUTs Under High-Temperature Conditions

PMUTs have been widely studied in recent years, particularly those based on the SOI (silicon-on-insulator) process, which have been partially commercialized and are extensively used in advanced applications such as ultrasonic ranging and spatial positioning. However, there has been little research o...

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Main Authors: Haochen Lyu, Ahmad Safari
Format: Article
Language:English
Published: MDPI AG 2025-02-01
Series:Applied Sciences
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Online Access:https://www.mdpi.com/2076-3417/15/5/2428
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author Haochen Lyu
Ahmad Safari
author_facet Haochen Lyu
Ahmad Safari
author_sort Haochen Lyu
collection DOAJ
description PMUTs have been widely studied in recent years, particularly those based on the SOI (silicon-on-insulator) process, which have been partially commercialized and are extensively used in advanced applications such as ultrasonic ranging and spatial positioning. However, there has been little research on their high-temperature reliability, a critical area for their use in extreme environmental conditions. In this study, we investigate the high-temperature characteristics of air-coupled PMUTs based on SOI under various structural conditions, employing both finite element analysis (FEA) and experimental validation. We assess the performance of PMUTs at elevated temperatures by examining key parameters such as resonant frequency, the electromechanical coupling coefficient, mechanical amplitude, and warpage, all analyzed as functions of temperature. The experimental results show that temperature-induced drift becomes more significant as the back cavity size increases and the top silicon layer thickness decreases. These findings are consistent with the trends observed in the finite element analysis. Specifically, a PMUT with a back cavity diameter of 1000 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi mathvariant="sans-serif">μ</mi></semantics></math></inline-formula>m and a top silicon thickness of 4 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi mathvariant="sans-serif">μ</mi></semantics></math></inline-formula>m exhibits a temperature drift rate of up to 47.3% when the operating temperature rises from room temperature to 200 °C. Furthermore, at elevated temperatures, the maximum electromechanical coupling coefficient improves by 68.6%, and the mechanical amplitude increases by 66.1%. Heating experiments using a 3D profiler reveal that warpage increases from 0.3 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi mathvariant="sans-serif">μ</mi></semantics></math></inline-formula>m to 2.15 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi mathvariant="sans-serif">μ</mi></semantics></math></inline-formula>m as the temperature reaches 150 °C. These findings offer important theoretical insights into the temperature-induced drift behavior of PMUTs under high-temperature conditions. This study provides a comprehensive understanding of the performance variations of PMUTs, including changes in electromechanical coupling, mechanical amplitude, and structural warpage, which are critical for their reliable operation in extreme environments. The results presented here can serve as a foundation for the design and optimization of PMUTs in applications that require high-temperature stability, ensuring their enhanced reliability and performance in such demanding conditions.
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spelling doaj-art-a4b32443c8674ff99459872e35f4efa02025-08-20T02:57:40ZengMDPI AGApplied Sciences2076-34172025-02-01155242810.3390/app15052428Performance Analysis of Scandium-Doped Aluminum Nitride-Based PMUTs Under High-Temperature ConditionsHaochen Lyu0Ahmad Safari1Department of Materials Science and Engineering in Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USADepartment of Materials Science and Engineering in Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USAPMUTs have been widely studied in recent years, particularly those based on the SOI (silicon-on-insulator) process, which have been partially commercialized and are extensively used in advanced applications such as ultrasonic ranging and spatial positioning. However, there has been little research on their high-temperature reliability, a critical area for their use in extreme environmental conditions. In this study, we investigate the high-temperature characteristics of air-coupled PMUTs based on SOI under various structural conditions, employing both finite element analysis (FEA) and experimental validation. We assess the performance of PMUTs at elevated temperatures by examining key parameters such as resonant frequency, the electromechanical coupling coefficient, mechanical amplitude, and warpage, all analyzed as functions of temperature. The experimental results show that temperature-induced drift becomes more significant as the back cavity size increases and the top silicon layer thickness decreases. These findings are consistent with the trends observed in the finite element analysis. Specifically, a PMUT with a back cavity diameter of 1000 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi mathvariant="sans-serif">μ</mi></semantics></math></inline-formula>m and a top silicon thickness of 4 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi mathvariant="sans-serif">μ</mi></semantics></math></inline-formula>m exhibits a temperature drift rate of up to 47.3% when the operating temperature rises from room temperature to 200 °C. Furthermore, at elevated temperatures, the maximum electromechanical coupling coefficient improves by 68.6%, and the mechanical amplitude increases by 66.1%. Heating experiments using a 3D profiler reveal that warpage increases from 0.3 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi mathvariant="sans-serif">μ</mi></semantics></math></inline-formula>m to 2.15 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi mathvariant="sans-serif">μ</mi></semantics></math></inline-formula>m as the temperature reaches 150 °C. These findings offer important theoretical insights into the temperature-induced drift behavior of PMUTs under high-temperature conditions. This study provides a comprehensive understanding of the performance variations of PMUTs, including changes in electromechanical coupling, mechanical amplitude, and structural warpage, which are critical for their reliable operation in extreme environments. The results presented here can serve as a foundation for the design and optimization of PMUTs in applications that require high-temperature stability, ensuring their enhanced reliability and performance in such demanding conditions.https://www.mdpi.com/2076-3417/15/5/2428scandium-doped aluminum nitride (AlScN)piezoelectric micromachined ultrasonic transducers (PMUTs)high-temperature performance
spellingShingle Haochen Lyu
Ahmad Safari
Performance Analysis of Scandium-Doped Aluminum Nitride-Based PMUTs Under High-Temperature Conditions
Applied Sciences
scandium-doped aluminum nitride (AlScN)
piezoelectric micromachined ultrasonic transducers (PMUTs)
high-temperature performance
title Performance Analysis of Scandium-Doped Aluminum Nitride-Based PMUTs Under High-Temperature Conditions
title_full Performance Analysis of Scandium-Doped Aluminum Nitride-Based PMUTs Under High-Temperature Conditions
title_fullStr Performance Analysis of Scandium-Doped Aluminum Nitride-Based PMUTs Under High-Temperature Conditions
title_full_unstemmed Performance Analysis of Scandium-Doped Aluminum Nitride-Based PMUTs Under High-Temperature Conditions
title_short Performance Analysis of Scandium-Doped Aluminum Nitride-Based PMUTs Under High-Temperature Conditions
title_sort performance analysis of scandium doped aluminum nitride based pmuts under high temperature conditions
topic scandium-doped aluminum nitride (AlScN)
piezoelectric micromachined ultrasonic transducers (PMUTs)
high-temperature performance
url https://www.mdpi.com/2076-3417/15/5/2428
work_keys_str_mv AT haochenlyu performanceanalysisofscandiumdopedaluminumnitridebasedpmutsunderhightemperatureconditions
AT ahmadsafari performanceanalysisofscandiumdopedaluminumnitridebasedpmutsunderhightemperatureconditions