Ultrahigh Vacuum Instrumentation

Ultrahigh Vacuum Instrumentation

Satoru Emori (Senior Undergraduate Student)

In order to characterize material structures and phenomena at the nanometer-scale, we must minimize contamination that would obscure experimental results. We attain a very pristine environment for nanoscale characterization in an ultrahigh vacuum (UHV) system.

UHVSYS

Omicron UHV VT STM/AFM

 

This UHV system, manufactured by Omicron Nanotechnology, houses a scanning tunneling microscope (STM) and a Kelvin probe force microscope (KPFM). It also includes a sample preparation chamber equipped with an electron-beam metal evaporator. An ionization pump, occasionally backed by a titanium sublimation pump, maintains the system at a pressure of about 10-11 torr. To find out more about experiments conducted with the UHV system, please refer to this page.

 

We have built an apparatus to deposit organic molecules on nanostructures without contaminating the analysis chamber. We have integrated a new deposition chamber into our existing UHV system, and a precision leak valve that allows for controlled deposition of organic molecules. The base pressure inside the chamber, which is around 10-9 torr, is attained by a turbomolecular pump. During deposition, an ionization gauge monitors the pressure, from which the quantity of molecules deposited on the sample can be determined.

With this additional UHV deposition setup, we can investigate how adsorbed molecules change the electronic properties of the nanostructured materials. Specifically, we plan to characterize the electronic properties of noble metal nanostructures and their interaction with various adsorbates of organic molecules. We use the STM and KPFM to measure the local electronic density of states and the work function, respectively, of the nanostructures.