NQCP - Life in Quantum - Research Assistant Faculty, Rosa E. Diaz, Purdue University

Atomic-Scale Analysis of Heterogeneous Interfaces: Developing Metrics for Quantum System

Heterogeneous interfaces in quantum devices often undergo structural and chemical transformations when integrating dissimilar materials, leading to various forms of disorder that can impact their stability and performance. This talk will highlight how atomic-resolution scanning transmission electron microscopy (STEM) provides a powerful approach to identify, quantify, and characterize these interfaces at the atomic scale.

We will present electron microscopy studies across different interfaces in superconductor-semiconductor systems used for quantum computation as well as nitride heterostructures used most commonly in optoelectronic devices. By leveraging high-resolution imaging, spectroscopy, and quantitative analysis, we extract critical interface characteristics such as roughness, bonding states, and chemical inhomogeneities, linking them to fabrication processes and electronic measurements. For example, in Al/semiconductor interfaces, we assess the bonding states of Al to determine the presence of metallic or oxidized species, providing insights into oxidation behavior and material stability.

Through these investigations, we demonstrate how atomic-resolution electron microscopy supports a metric-driven approach to studying disorder at heterogeneous interfaces, offering useful insights into interface quality. These information can help optimize material growth and fine-tune fabrication processes, ultimately contributing to the advancement of next-generation devices.