Michael Hennessy is currently pursuing a PhD as part of the TEMUL group under the supervision of Prof. Ursel Bangert. The project, funded by Volkswagenstiftung, began in 2017 and is a collaboration between researchers from the University of Limerick, the Peter Grünberg Institute (situated in the Forchungszentrum Jülich, Germany), and the University of Göttingen, Germany. The project is focused on creating new single photon sources by engineering monolayer-thick semiconductors on the atomic scale. TEMUL’s role in the project involves analysis of single photon emission from ion-implanted monolayer transition metal dichalcogenides (TMDs) using STEM, HAADF and EELS. The implanted TMDs will later be incorporated into non-classical LEDs for use in quantum information processing and quantum metrology.

As part of Michael’s training for the project, he recently spent two weeks working in Forschungszentrum Jülich. There, under the supervision of Dr. Hongchu Du of the Ernst Ruska-Centre, he had the opportunity to work on the FEI Titan PICO in order to obtain high resolution TEM and electron holography images. The PICO is a unique Cc and Cs corrected fourth generation field emission gun TEM equipped with a high-brightness electron gun and a monochromator unit. A high resolution TEM image of a pristine MoSe2 sample is shown above. Michael also spent time doing high resolution STEM analysis of the same sample using the FEI Titan-S.

In addition to training in analytical techniques, Michael spent several days trying several sample preparation techniques for transferring thin layers of TMDs onto TEM grids. Working with members of Prof. Beata Kardynal's group at the Peter Grünberg Institute, Michael used PDMS dry stamping and PPC flow transfer methods to apply thin flakes of MoSe2 onto TEM grids. This allowed a comparison to be drawn up between different methods, and provided information which could potentially help improve the sample preparation process in the TEMUL lab.

Michael's stay in Jülich was concluded with discussions regarding the direction of the project and work to be done over the coming months.