Micron Scale Positioning in Ultra High Vacuum For PEEM

K. Siegrist, V. Ballarotto and E.D. Williams
Laboratory for Physical Science
University of Maryland, College Park


Photoelectron emission (PEEM) is a potentially powerful technique for real-time, sub-micron imaging of organic, metal and semiconductor electronic devices. It is non-intrusive with broad imaging capabilities, but application has been limited due to lack of understanding of imaging contrast mechanisms. More refined control of sample positioning was necessary to further understanding of some of these mechanisms

We are using a newly developed* 5-axis nonmagnetic in-vacuum stage for micron-scale positioning of samples we investigate with PEEM. This compact in-vacuum system has eliminated vibration problems, while the piezo-driven motors give consistent, repeatable control of sample position with linear step size 1µm and an angular step of 1/360°.

For example, precise measurements of angle with respect to the microscope axis are now possible. Below are shown images demonstrating the strong effect of small variations in the angular orientation of the sample with respect to the normal. The 16 µm wide raised lines on this titanium sample are 1/2 µm tall. The sample is tilted 1/3° with respect to the PEEM axis in the left and right images; the bright edge is tipped toward the microscope. The center image shows the sample oriented normal to the PEEM.

* Developed by Thermionics, Northwest as custom order for LPS PEEM program.