High-sensitivity noncontact atomic force microscope/scanning tunneling microscope (nc AFM/STM) operating at subangstrom oscillation amplitudes for atomic resolution imaging and force spectroscopy

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Oral A., GRIMBLE R., ÖZER H. Ö., PETHICA J.

REVIEW OF SCIENTIFIC INSTRUMENTS, cilt.74, sa.8, ss.3656-3663, 2003 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 74 Sayı: 8
  • Basım Tarihi: 2003
  • Doi Numarası: 10.1063/1.1593786
  • Dergi Adı: REVIEW OF SCIENTIFIC INSTRUMENTS
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.3656-3663
  • Orta Doğu Teknik Üniversitesi Adresli: Hayır

Özet

We describe a new, highly sensitive noncontact atomic force microscope/scanning tunneling microscope (STM) operating in ultrahigh vacuum (UHV) with subangstrom oscillation amplitudes for atomic resolution imaging and force-distance spectroscopy. A novel fiber interferometer with similar to4x10(-4) A/rootHz noise level is employed to detect cantilever displacements. Subangstrom oscillation amplitude is applied to the lever at a frequency well below the resonance and changes in the oscillation amplitude due to tip-sample force interactions are measured with a lock-in amplifier. Quantitative force gradient images can be obtained simultaneously with the STM topography. Employment of subangstrom oscillation amplitudes lets us perform force-distance measurements, which reveal very short-range force interactions, consistent with the theory. Performance of the microscope is demonstrated with quantitative atomic resolution images of Si(111)(7x7) and force-distance curves showing short interaction range, all obtained with <0.25 Angstrom lever oscillation amplitude. Our technique is not limited to UHV only and operation under liquids and air is feasible. (C) 2003 American Institute of Physics.