The analysis chamber hosts a VT XA STM (ScientaOmicron). The microscope has recently (2019) been upgraded so that non-contact AFM via QPlus sensors became possible. Most of our users run perform STM characterization of their samples in conjunction with their (spectrocopy) studies at other beamlines. Using vacuum suitcase at SPM lab it is possible to transfer the samples to/from STM from/to most of the beamlines at 1.5 GeV ring and HiPPiE at 3 GeV ring without breaking the ultra-high vacuum conditions.

Analysis chamber specifications

Base pressure7×10-11 mbar
Sample heatingYes, up to ~ 370o C / 650 K via boraelectric heater, Lakeshore controller
Scanning at elevated temperature possible
Sample coolingYes, down to -163o C / 110 K via LN2 bath cryostat
~ 12 hours stable operation at 110 K per one cryostat filling
Ports for atom/molecular
sources		DN40CF × 2 if long-distance microscope is not needed
Imaging during deposition is possible
Approx distance flange-sample ~ 160 mm at 40o incidence
StorageCarousel with 12* sample slots
Table with main parameters of the analysis chamber.

*Actual number of available slots is normally less than that because some slots are occupied with a tip carrier, few tips/QPlus sensors, test samples, etc. More storage may be available upon a timely request.

Microscope specifications

Coarse tip positioning range, mm~ 10 × 10 × 5
Fine positioning/scanning range, μm~ 19 × 19 (12 × 12)
Max / min sample temperature, oC (K)~ 370 (650) / -163 (110)
Tip cooling / cryo-STMNo
Imaging at arbitrary temperatureYes
Lockin amplifierSRS830
Techniques availableSTM, STS, dI/dV mapping, ncAFM**, dF/dV (~KPFM) and dF/dZ mapping
Table with main parameters of the microscope.

** Due to poor control over the tip shape at room temperature, the performance of all ncAFM techniques is not guaranteed.

Resolution in STM and ncAFM

STM

Si(111)-(7×7) tunneling conditions Vbias = +1.55 V, It = 130 pA

stm-ar1
Left panel: topography map Z(X,Y). Right panel: height profile along the white line.
AFM

Si(111)-(7×7) scanning conditions: Vbias = 0.00 V, df = -27.1 Hz (f = 28.04 kHz)

STM-ncAFM-resolution
Left panel: topography map Z(X,Y), inset in the top-right is a fast Fourier transform of this image. Right panel: height profile along the indicated line.
Comparison between STM and ncAFM imaging/resolution

Sample: SiC(0001), STM: Vbias = +1.25 V, It = 230 pA AFM: Vbias = 0.00 V, df = -20.1 Hz (f = 28.04 kHz)

STMvsAFM