Design and operation of a versatile, ultrahigh vacuum, low temperature scanning probe microscope

Abstract

The design and operation of an ultrahigh vacuum, liquid nitrogen or helium cooled scanning probe microscope system are presented. Key construction features that reflect crucial experimental criteria will be highlighted. Following from a recently devised approach to low temperature microscopy, cooling of the Besocke-style [Surf. Sci. 181, 145 (1987)] microscope assembly is performed by housing the microscope assembly in cryogenic shields which are coupled to a low vibration flow cryostat. The microscope, however, has been designed to accommodate different types of probes including tunneling and force sensors, and this functionality offers significant flexibility. As a demonstration of temperature and microscope stability, scanning tunneling microscopy measurements at 83K, using liquid nitrogen as the cryogen, will be shown on a flat metallic Ag(111) surface. In this temperature range, we measure a drift rate of 0.34Å∕h in the distance between the tip and sample as a result of ∼2mK∕h temperature drift at the microscope base, and we enumerate the procedure for establishing this stability.