Research

Correlative Microscopy of Semiconductors

Correlative microscopy integrates multiple high resolution characterization techniques to provide a comprehensive understanding of semiconductor materials and devices across length scales. By combining structural imaging methods such as transmission electron microscopy with three dimensional compositional techniques including atom probe tomography, it becomes possible to directly relate atomic scale chemistry to crystallography, defects, and device architecture. This approach is particularly important for modern semiconductors, where continued scaling, complex heterostructures, and low dopant concentrations place stringent demands on both spatial resolution and quantitative accuracy.

Correlative workflows enable the identification of processing induced damage, dopant redistribution, and defect mediated segregation that may not be apparent from a single technique alone. Focused ion beam based site specific preparation further supports precise targeting of regions of interest within functional devices. Overall, correlative microscopy provides a powerful and versatile framework for semiconductor metrology, reliability assessment, and the development of next generation electronic and optoelectronic materials.

Microscopy of 2D Materials

2D materials are attracting increasing interest due to their extraordinary mechanical, optical, magnetic, electrical, thermal, and electronic properties such as a high Young’s modulus, excellent mobility and Fermi velocity, the existence of the Dirac cone, and quantum hall effects, etc.

Silicene is an emerging 2D material and is predicted to play a very important role in the semiconductor industry owing to its compatibility with the present Si-based semiconductor market. We are seeking more efficient methods to synthesize, characterize, and apply this potential 2D material.

In our group, we are also working on preparation and characterization of 2D materials including phosphorene, Indium Nitride, and Gallium Nitride (among others) by TEM characterization techniques including EELS, HAADF, and STEM.

Metallic Microstructures

The increased demands of automotive companies for the use of advanced high strength steels (AHSS) as well as press hardened steels (PHS) has been driven by the need to reduce vehicle weight, thereby improving fuel efficiency, while maintaining or improving vehicle safety. Despite all the advantages of using zinc-coted steels, in the zinc coating process, coating fractures usually form in the early stages of press forming. The fracture forming might derive from liquid metal induced embrittlement. This project is aimed at investigating the origin of micro-cracking in zinc-coated steels and attempting to find the best solution.

The push to develop new steels has resulted in important changes in steel compositions. The impact of these composition changes on the thermo-mechanical processing of AHSS has yet to be explored. The aim of the present project is to develop a physical model for the hot-rolling of novel low-alloy steels that contain alloying additions beyond the traditionally used range. Fundamental studies will be carried out on the interaction of alloying elements at moving boundaries and on precipitate evolution during hot rolling employing state-of-the-art microscopy techniques.

Focused Ion Beam Technology

Dualbeam FIB/SEM instruments have always been the final word in TEM sample preparation, but in recent years they have become indispensable tools for the prototyping and fabrication of micro-optical devices, metamaterials, and MEMS.

In our group, we are well equipped to study the technique and its applications: we are actively researching theories of ion-solid interaction, cutting edge instrumentation, and the design of metamaterials for future optical devices. Close relationships with businesses in the field provide funding, equipment, and inspiration for new and impactful projects.

We are actively working on understanding and mitigating damage induced by local heating, knock-on interaction, and radiolysis in soft materials in order to develop bio- and liquid-based imaging and tomography. The study moves beyond the realm of Ga+ FIB to include plasma Xe+ FIB and trimer-source Ne+/He+ FIB

Computational Image Processing

Automated image and spectroscopic acquisition in microscopy has opened doors to sizeable amount of data. Manually processing these large amounts of data takes too much time and is not possible. Moreover, collecting data with the SEM is slow. Nowadays, with the use of image processing techniques and programming, we can speed up these processes.

We put substantial focus on developing novel segmentation and image processing techniques. These are applied to finding an improved way to reconstruct 3D SEM images, and are also working on detection of features of interest during data acquisition to speed up large-volume tomography applications.

We also aim to increase the efficiency of phase detection and classification in complex, heterogeneous and multiphase structural materials (i.e. Steel/Concrete) by utilizing a convolutional neural network for object classification.