EXPLORING CORRELATIVE MICROSCOPY METHODOLOGIES FOR ENHANCED IMAGING AND ANALYSIS WITH HELIUM ION MICROSCOPE

Correlative microscopy plays a vital role in scientific research and material analysis by offering a valuable solution to integrate diverse imaging techniques, resulting in a comprehensive understanding of complex samples. Combining Secondary Electron (SE), Scanning Transmission Ion Microscopy (STIM), and Secondary Ion Mass Spectrometry (SIMS) in one apparatus using a He+/Ne+ ion beam, we can establish meaningful connections between the morphology, crystal structure, and chemistry of a given sample on a nanometre scale. This approach delves deep into the complexities of material characteristics such as semiconductors, biological processes, etc. However, one of these three correlative approaches, STIM, has potential applications that still need to be studied and compared to similar existing methods.
Before delving into STIM imaging, we initiated our study by examining ion-induced damage effects before and during imaging on the sample. For this aim we performed preliminary experiments related to Ga+ and He+ ion irradiation on thin lamellae of silicon and aluminium. Depending on the experimental conditions, we investigated the top and bottom surface morphologies, as well as a structural transformation from crystalline to amorphous material.
Subsequently, to understand STIM applications, we compared STIM imaging with existing comparable imaging techniques such as Transmission Kikuchi Diffraction (TKD), Backscattered Electrons (BSE), and SE. Additionally, we expanded the capabilities of STIM imaging by conducting Time of Flight (ToF) measurements using a separate apparatus to explore the potential for complementary studies within the STIM technique.
Towards the conclusion of our research, we focused on the materials science applications of ion beam microscopy techniques namely SE, SIMS and STIM techniques. Our initial focus was on studying dopant profiling by analysing SE-generated contrast with a helium ion beam. In the subsequent stage of our correlative approach, we established connections between SIMS, SE imaging, and other techniques to investigate perovskite solar cell materials. In the final segment of our correlative approach, we attempted to correlate STIM with SIMS. While this endeavour had limited success, it did provide valuable insights in that direction.