Cryogenic variable temperature ultrahigh vacuum scanning tunneling microscope for single molecule studies on silicon surfaces

E. T. Foley, N. L. Yoder, N. P. Guisinger, M. C. Hersam

Research output: Contribution to journalArticle

52 Citations (Scopus)

Abstract

The design and performance of a variable temperature ultrahigh vacuum (UHV) scanning tunneling microscope (STM) is presented. This STM operates from 8.2 to 300 K in a UHV environment with a base pressure of less than 6 × 10 -11 Torr. Cooling is achieved from 300 to 80 K within 3.5 h and from 80 to 8.2 K within 4.5 h. The base temperature of 8.2 K is maintained at a liquid helium consumption rate of 0.9 1/h. This design allows for direct optical access to the tip-sample interface and direct line-of-sight dosing while the sample is mounted in the STM. The STM tip may be coarse translated laterally in two dimensions through a 6-mm-diam area at all temperatures. With the feedback loop off, the drift in the tip-sample spacing is approximately 0.008 Å/min at 8.2 K. Atomic resolution feedback controlled lithography is performed on hydrogen passivated Si(100) and differential tunneling conductance maps are gathered for isolated cyclopentene molecules on unpassivated Si(100), thus demonstrating that this system is well suited for studying single molecules on silicon surfaces from 8.2 to 300 K.

Original languageEnglish
Pages (from-to)5280-5287
Number of pages8
JournalReview of Scientific Instruments
Volume75
Issue number12
DOIs
Publication statusPublished - Dec 1 2004

ASJC Scopus subject areas

  • Instrumentation

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