Observation of harmonic current oscillations on partially oxidized Si(111) surfaces by scanning tunneling microscopy

Harmonic oscillations of the tunneling current on partially oxidized Si(111) and on Au clusters deposited on these surfaces were observed by scanning tunneling spectroscopy (STS). The frequencies of the current oscillations are independent of the bias voltage. They are the product of a basic frequency (29.99±0.01 Hz) times an integer N. It is assumed that the basic frequency is the reciprocal of the capture time of an electron in an individual trap, that N is related to the number of traps taking part in the charge-discharge processes during STS, and that the electron traps in the small area participating in the local STS are functionally correlated by some unknown mechanism which reduces the electron capture time proportional to 1/N.