IMAGING AND TRANSFER OF SINGLE ATOMS IN THE SCANNING TUNNELING MICROSCOPE

M. Kleber, Christian Bracher, M. Riza

Michaël Rosticher, F. R. Ladan, J. P. Maneval +6 more

WE REPORT THE DETECTION OF SINGLE ELECTRONS USING A 6 NM-THICK, 100 NM-WIDE, NB0.7TI0.3N SUPERCONDUCTING STRIP DEPOSITED ON A SIOX/SI SUBSTRATE. WHEN BIASED SLIGHTLY BELOW THE CRITICAL CURRENT, A MEANDER-SHAPED DEVICE, NOT ONLY DETECTS SINGLE PHOTONS, BUT ALSO COUNTS THE SINGLE KEV ELECTRONS ISSUED FROM A SCANNING ELECTRON MICROSCOPE (SEM) WITH AN EFFICIENCY APPROACHING UNITY. THE RESPONSE TIME IS SHORT ENOUGH TO DISCRIMINATE THE INCIDENT ELECTRONS FROM THOSE BACKSCATTERED FROM THE UNDERLYING MATERIAL. IT IS THEREFORE POSSIBLE TO MAP THE ELECTRON DETECTIVITY AS WELL AS THE PHOTON DETECTIVITY ON THE SAME DEVICE. A CLEAR CORRELATION BETWEEN THE TWO MEASUREMENTS IS OBSERVED, WITH A SUPERIOR SPATIAL RESOLUTION THOUGH (AROUND 100 NM) FOR THE SEM MAPPING. IT ILLUSTRATES THE POTENTIAL USE OF THIS SINGLE ELECTRON MAPPING BY THE SEM METHOD TO CHARACTERIZE THE DETECTION HOMOGENEITY OF SSPDS

Andrew J. Mayne

Z.-H. Huang, Paul H. Cutler, T. E. Feuchtwang +1 more

We have developed a formal general approach for evaluating the WKB wave function in a forbidden region of a non-separable potential in a three-dimensional space. The wave function is described by two sets of orthogonal wave-fronts, the equi-phase and equi-amplitude surfaces, or equivalently by two sets of paths defined to be normal to these surfaces respectively. We have extended a Huygens type construction to the forbidden region to obtain the multi-dimensional wave function. The construction determines the wave-fronts and the paths. It is found that the equations for the paths obtained from the construction are coupled to each other and do not reduce to a set of ordinary differential equations. However, if the incident wave is normal to the turning surface, the equations satisfied by the paths can be de-coupled. These equations are found to be equivalent to Newton's equations of motion for the inverted potential and energy. This characteristics has been used to calculate the current density distribution for an STM. In this paper, we use the same approach to derive the expressions for the lateral resolutions and corrugations for a model STM.

Philip Willke, Yujeong Bae, Kai Yang +7 more