Aberration Corrected FE-LEEM P90 now capable of 2.0nm Resolution

As a result of a collaboration with Dr. Rudolf Tromp at the IBM Watson Research Center in Yorktown Heights, USA, an ultimate resolution of 2.0nm has been achieved. Test measurements have been performed on thin graphene layers on SiC(111). Areas with different numbers of carbon layers show different gray levels. The data below shows a LEEM image where step contrast is seen in areas with the same layer number. The profile has been averaged over strips 10 pixels wide, as indicated in the image by the yellow boxes. Based on a 20% - 80% criterion the step width is determined to be 1.96nm.

Details provided here (PDF download).

Ultimate resolution of 4.1nm achieved with the FE-LEEM P90

New data of the second FE-LEEM P90 delivered and assembled by SPECS shows an ultimate resolution below 5nm, down to 4.1nm.

The data shown has been integrated within the rectangles to generate the profiles.

Si(100)-2x1: Dark field image taken at 3.5eV kinetic energy. Field of view is 1260nm:

Si(100)-2x1: Dark field image taken at 3.5eV kinetic energy. Field of view is 840nm:

The 16 micrometer field of view image shows a silver island on Si(111), consisting of Ag crystallites with (100) and (111) orientation. The bandstructures shown below are taken from the areas within the red circles, covering polar emission angles from +90 to -90 degrees. The data has been acquired in the laboratory using the SPECS focussed UVS300 UV source . This source is delivering a HeI (21eV) and HeII (40eV) photon flux density that is comparable to synchrotron radiation sources, enabling acquisition times of only 20 seconds for each image.

Scanning the entrance slit the whole surface band structure can be recorded. The images below are k-space maps at constant binding energy with ΔE=0.16eV.