Careful Heating Unlocks Unprecedented Pressure Sensitivity in Semiconductor Materials

A simple heat treatment has been shown to significantly improve the pressure sensitivity of semiconductor materials used in devices such as cell phones, sensors and energy harvesters.

In a new study published in Nature Communications, researchers from the University of Michigan (U-M) demonstrated that annealing a scandium aluminum nitride film at 700 degrees Celsius for two hours increases its piezoelectric response by a factor of eight compared with current commercial materials.

Annealing enhances piezoelectric properties for electronics and sensors

Piezoelectricity is the ability of certain materials to generate electrical charge in response to mechanical stress. This property is crucial in many everyday technologies. In mobile phones, piezoelectric materials help filter signals to reduce noise. In vehicles, they are used to activate airbags and monitor tire pressure.

The team found that the annealing process reorients tiny crystal grains in the thin film material, enhancing the material's overall electrical response to pressure.

“The piezoelectric response of this material is a contribution from structural ‘grains’ oriented in a particular direction. When the films are just grown, these grains are often not perfectly oriented, with some grains not effectively contributing to the overall piezoelectric response,” explained Shubham Mondal, U-M doctoral student in electrical and computer engineering and co-first author of the study.

“The annealing process gives some additional energy to the film, allowing the grains to become better oriented. And that’s partly how their piezoelectric response is increasing,” said Md Mehedi Hasan Tanim, U-M doctoral student in electrical and computer engineering and co-first author of the study.

Future directions

Because the new process is compatible with existing manufacturing standards, it offers a low-cost way for industry to boost the performance of piezoelectric devices. Potential applications range from aerospace and health care sensors to energy harvesting systems and ultrasound imaging.

The researchers are now planning to apply this annealing method to other materials, such as scandium aluminum nitride films produced by advanced techniques like molecular beam epitaxy. This typically yields higher-quality materials, which could benefit their piezoelectric response even further by using such an annealing approach.

Reference: Mondal S, Tanim MMH, Baucom G, et al. Unprecedented enhancement of piezoelectricity of wurtzite nitride semiconductors via thermal annealing. Nat Commun. 2025;16(1):4130. doi: 10.1038/s41467-025-59179-2

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