Researchers from the University of Wisconsin-Madison, Lawrence Livermore National Laboratory, and the University of California, Riverside have developed a new method to identify defects in aluminum oxide, a material commonly used in the energy industry, particularly in the fabrication of quantum dot qubits. Their work, published in the journal Nature Communications, could have significant implications for improving the performance and reliability of these advanced technologies.
Aluminum oxide is often used as a gate dielectric in semiconductor devices, including quantum dot qubits. However, defects in this material can lead to charge noise, which can limit the coherence and performance of these devices. To address this issue, the researchers developed a new approach using cryogenic electrostatic force microscopy (EFM) to characterize defects in aluminum oxide grown by atomic layer deposition (ALD) on bulk silicon.
The researchers found that their EFM technique could provide highly resolved maps of the surface potential of the aluminum oxide, as well as detect single-electron charging processes that reflect the spectral structure of underlying defects. By using detailed electrostatic modeling, they were able to map tip-backgate charging voltages onto defect transition energies, allowing them to identify specific types of defects, such as aluminum vacancies and impurities like carbon, oxygen, or hydrogen.
The researchers compared their experimental results to density functional theory (DFT) calculations to confirm the identity of the defects. This approach could provide a powerful new tool for exploring defect structures in solid-state qubits and other semiconductor devices, ultimately leading to improved performance and reliability.
In the energy industry, this research could have practical applications in the development of more efficient and reliable quantum computing technologies, which could be used to optimize energy systems, improve energy storage, and advance other energy-related applications. Additionally, the ability to identify and characterize defects in aluminum oxide could have implications for the development of more advanced and reliable semiconductor devices for a wide range of energy applications.
Source: Nature Communications, “A scanning probe microscopy approach for identifying defects in aluminum oxide” (2023)
This article is based on research available at arXiv.