Imaging and Identification of 2D Indium Selenide Semiconductor

At the beginning of summer a research group at the Ohio State University sent two 2D Indium Selenide semiconductor samples to my professor to use for research, but first the crystals had to be located on their respective substrates. I set about the creation of an imaging system using white light to identify the 2D crystals on their respective substrates as they are too small to be seen by eye. As a preliminary step the magnification of the imaging system, which is the per pixel distance of generated images, was determined. For the identification process, one of the substrates was placed upon a two axis stage in the imaging plane, allowing the lnSe crystal to be searched for via the live feed of the camera. Pictures were taken of each region containing peculiar inhomogeneities and thus possible crystals. By counting pixels and applying the calculated magnification of the system, sizes of plausible crystals were estimated. Those crude measurements were then compared with the measurements provided by the fabricators, allowing for the identification of the true crystal. Its position was subsequently marked with a scourer. This exact process was repeated for the second crystal sample. After identification, I tried to collect photoluminescent data with a pre-existing experiment but no spectral response was observed at room temperature, a fact supported by literature data. The conclusion was to build a new experiment that incorporated, among other things, a cryostat to keep the sample cold in order to collect spectral data. Construction of this experiment became a cooperative project between a grad student and I that continued into the fall. Ultimately my efforts in imaging and locating the crystals will enable their use in future research of the group on 2D semiconductors.