Scanning tunneling potentiometry implemented into a multi-tip setup by software.

We present a multi-tip scanning tunneling potentiometry technique that can be implemented into existing multi-tip scanning tunneling microscopes without installation of additional hardware. The resulting setup allows flexible in situ contacting of samples under UHV conditions and subsequent measurement of the sample topography and local electric potential with resolution down to Å and µV, respectively. The performance of the potentiometry feedback is demonstrated by thermovoltage measurements on the Ag/Si(111)-(√3×√3)R30° surface by resolving a standing wave pattern. Subsequently, the ability to map the local transport field as a result of a lateral current through the sample surface is shown on Ag/Si(111)-(√3×√3)R30° and Si(111) - (7 × 7) surfaces.

Element specific surface reconstructions of islands during surfactant-mediated growth on Si (111).

The early stages of surfactant- (As, Sb) mediated homoepitaxial growth on Si (111) are examined by scanning tunneling microscopy and extensive ab initio calculations of Si(n) clusters (n

Direct observation of subcritical fluctuations during the formation of strained semiconductor islands

We have directly imaged subcritical fluctuations during the nucleation phase of three-dimensional islands in strained layer epitaxy. The fluctuations are defect mediated and are found to be large even at low growth temperatures. We attribute the existence of large fluctuations to the time dependence of the supersaturation. This indicates classical nucleation concepts are relevant, even at low growth temperatures.