The Major Research Instrumentation award supports the development of a novel cost-efficient electron microscope capable of imaging the top-most layers of surfaces with high spatial resolution at the College of New Jersey. The scope of the project is to combine the fundamental concepts of scanning electron (SEM) and scanning probe microscopies (SPM) into a single instrument called "Near Field Emission Scanning Electron Microscopy" (NFESEM). The use of low energy electrons NFESEM will have an impact over many areas including biological, medical, data storage, computing and renewable energy. The device will immediately provide an alternative, high resolution surface imaging device to researchers in both New Jersey and Eastern Pennsylvania. The results from this project will be incorporated in course curricula at The College of New Jersey. Undergraduate students involved in the project will be trained and acquire expertise in these techniques. The instrumentation will help underpin forthcoming technological developments especially in the area of ultra large scale integrated circuits and spintronics. Furthermore, the collaboration scheme which includes early career and well-established scientists and engineers will impact research on superconductivity, low energy electron spectroscopy, nano-device characterization, nanoparticle enabled drug delivery and more. Involvement of industrial partners will enhance the training and transfer of knowledge. The researchers will also use this as an opportunity to introduce underrepresented middle school and high school students from Trenton to basic microscopy and its applications.
NFESEM will provide a means of overcoming the limitations of conventional scanning electron microscopes (SEM) and opens the possibility to use lower primary beam energies (< 100 eV). In essence, NFESEM is an intermediate technique in which electrons are emitted from a needle tip via field electron emission, and then impinge on and interact with the sample. As a result, electrons are ejected from the sample surface and detected and an electron spin detector will be incorporated into the system for polarization analysis of ejected secondary electrons. The NFESEM coupled with a spin polarimetry will enable SEM with polarization analysis capable of nanometer magnetic imaging, in particular low dimensional magnetic systems. The microscope will be equipped with a cryogen-free electro-magnet that is constructed to magnetize the sample of interest with a magnetic field up to 3,000 Gauss. The design and the control unit added to the scanning probe microscope will allow for high speed imaging, which is essential to simulate the imaging capabilities of standard scanning electron microscopes. The unique operating mode of the microscope, coupled with the polarimeter, generates three characteristic signals: 1) field emission current; 2) variations in the backscattered and secondary electron signal; and 3) a three dimensional surface spin asymmetry. This ensemble will enable nanometric imaging of magnetic materials; in particular, low dimensional magnetic systems. The NFESEMPA will be the first of its kind, and the proposed research team will be able to determine the advantages and/or disadvantages of using lensless scanning electron microscopy, c.f. contemporary SEMPA. Accordingly, this project will present an alternative method to generate a fine electron beam for high resolution imaging of atomically "smooth" surfaces.
