Normalization procedure for obtaining the local density of states from high-bias scanning tunneling spectroscopy
R. Rejali (TU Delft - QN/Quantum Nanoscience, TU Delft - QN/Otte Lab, Kavli institute of nanoscience Delft)
Laëtitia Farinacci (Kavli institute of nanoscience Delft, TU Delft - QN/Quantum Nanoscience, TU Delft - QN/Otte Lab)
A.F. Otte (TU Delft - QN/Otte Lab, Kavli institute of nanoscience Delft, TU Delft - QN/Quantum Nanoscience)
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Abstract
Differential conductance spectroscopy performed in the high bias regime - in which the applied voltage exceeds the sample work function - is a suboptimal measure of the local density of states due to the effects of the changing tunnel barrier. Additionally, the large applied voltage oftentimes makes constant-height measurement experimentally impractical, lending constant-current spectroscopy an advantageous edge; but the differential conductance in that case is even further removed from the local density of states due to the changing tip height. Here, we present a normalization scheme for extracting the local density of states from high bias scanning tunneling spectroscopy, obtained in either constant-current or constant-height mode. We extend this model to account for the effects of the in-plane momentum of the probed states to the overall current. We demonstrate the validity of the proposed scheme by applying it to laterally confined field-emission resonances, which appear as peak-shaped spectroscopic features with a well-defined in-plane momentum.
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