Kelvin probe force microscopy of the nanoscale electrical surface potential barrier of metal/semiconductor interfaces in ambient atmosphere

Abstract

This study deals with the preparation and characterization of metallic nanoinclusions on the surface of semiconducting Bi2Se3 that could be used for an enhancement of the efficiency of thermoelectric materials. We used Au forming a 1D alloy through diffusion (point nanoinclusion) and Mo forming thermodynamically stable layered MoSe2 nanosheets through the reaction with the Bi2Se3. The Schottky barrier formed by the 1D and 2D nanoinclusions was characterized by means of atomic force microscopy (AFM). We used Kelvin probe force microscopy (KPFM) in ambient atmosphere at the nanoscale and compared the results to those of ultraviolet photoelectron spectroscopy (UPS) in UHV at the macroscale. The existence of the Schottky barrier was demonstrated at +120 meV for the Mo layer and −80 meV for the Au layer reflecting the formation of MoSe2 and Au/Bi2Se3 alloy, respectively. The results of both methods (KPFM and UPS) were in good agreement. We revealed that long-time exposure (tens of seconds) to the electrical field leads to deep oxidation and the formation of perturbations greater than 1 µm in height, which hinder the I–V measurements.

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“…Conductive NSG01/TiN tips (150 kHz, 5.1 N/m) were used for Kelvin probe force measurements. The setpoint was stabilized in the range of 40–50%, and a 0.5 Hz scanning frequency was used . The topography was measured by oscillation at the first resonance frequency of the AFM tip.…”

“…The setpoint was stabilized in the range of 40−50%, and a 0.5 Hz scanning frequency was used. 19 The topography was measured by oscillation at the first resonance frequency of the AFM tip.…”

KPFM visualisation of the Schottky barrier at the interface between gold nanoparticles and silicon

“…1 In such investigations, Kelvin Probe Force Microscopy (KPFM) serves as a key instrument, since it allows measuring the variations of the local work function through the contact potential difference (CPD) for individual nanostructures. 2,12 It has recently been applied for AuNPs on TiO 2 by several groups. [9][10][11][13][14][15] In the present study, we used KPFM for analysing the geometry of the Schottky barrier formed by 55 nm AuNPs grafted on silicon with either n-or p-doping.…”

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“…[148] In such investigations, KPFM serves as a key instrument since it allows measuring the variations of the local work function through the CPD for individual nanostructures. [149,158] It has recently been applied for AuNPs on TiO2 by several groups. [18,156,157,[159][160][161] In this thesis, we used KPFM for analysing the profile of electric potential of the Schottky barrier formed by 50 nm AuNPs grafted on silicon with either n-or p-doping.…”