Data evaluation technique for electron-tunneling spectroscopy

Abstract

A systematic study of local-density-of-states ͑LDOS͒ deconvolution from tip-surface tunneling spectra is reported. The one-dimensional WKB approximation is used to simulate the process. A technique for DOS deconvolution from the electron-tunneling spectroscopy data is proposed. The differential conductivity normalized to its fit to the tunneling probability function is used as a method of recovering sample DOS. This explicit procedure does not use unconstrained parameters and reveals a better DOS deconvolution in comparison with other techniques. The advantage of this method is its feasibility for extracting two important physical parameters from experimental tunneling spectra: ͑i͒ local surface potential, and ͑ii͒ tip-sample distance. These values are the parameters used in the proposed fitting procedure. The local surface potential and the tip-sample distance retrieval are demonstrated by means of numerical simulations. Comparative scanning tunneling spectroscopy is proposed as an approach to eliminate the influence of the tip condition on the surface LDOS recovery.

Three-dimensional Wentzel-Kramers-Brillouin approach for the simulation of scanning tunneling microscopy and spectroscopy

“…(31) and (32) at U = V . The second term can be reexpressed following the literature [5,10,86], and the differential conductance at bias voltage V can be written as the sum of three terms,…”

“…One direction of recent theoretical research is focused on extracting surface local electronic properties from experimental STS data [5][6][7][8][9], which is the convolution of tip and sample electronic structures. Applying STS in the spin-polarized setup, this research line could be extended to the possible extraction of local spin polarization information of surfaces.…”

Simulation of spin-polarized scanning tunneling spectroscopy on complex magnetic surfaces: Case of a Cr monolayer on Ag(111)

“…The 1D WKB theory for nonmagnetic STS is a well established approach [5,35], see appendix A. Here, we extend it to spin-polarized systems, and adapt it to an atom superposition framework, which enables a computationally inexpensive calculation of tunneling properties based on first principles electronic structure data.…”

“…The progress of experimental techniques in the last two decades was remarkable, thus, more sophisticated theoretical models and simulation tools are needed to explain all relevant details of electron tunneling transport measurements [3,4]. STS theory and applications are recently focused on extracting surface local electronic properties from experimental differential conductance (dI/dV ) data [5][6][7][8][9]. The role of the tip electronic structure has been identified to be crucial on the dI/dV tunneling spectra, see e.g.…”

Atomic scale images of acceptors in III-V semiconductors

“…Feenstra proposed a normalization of the dI/dV signal with a smoothed overall conductivity (Ī/V ) [17]. Under the assumption that T(eV) is a smooth function without much structure this normalization would approximately cancel out the second term and the T(eV,eV,d) factor [59]. Then the dI/dV/(Ī/V ) signal would give a more accurate quantity.…”