A study of dopant incorporation in Te-doped GaAsSb nanowires using a combination of XPS/UPS, and C-AFM/SKPM

Abstract

We report the first study on doping assessment in Te-doped GaAsSb nanowires (NWs) with variation in Gallium Telluride (GaTe) cell temperature, using X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), conductive-atomic force microscopy (C-AFM), and scanning Kelvin probe microscopy (SKPM). The NWs were grown using Ga-assisted molecular beam epitaxy with a GaTe captive source as the dopant cell. Te-incorporation in the NWs was associated with a positive shift in the binding energy of the 3d shells of the core constituent elements in doped NWs in the XPS spectra, a lowering of the work function in doped NWs relative to undoped ones from UPS spectra, a significantly higher photoresponse in C-AFM and an increase in surface potential of doped NWs observed in SKPM relative to undoped ones. The carrier concentration of Te-doped GaAsSb NWs determined from UPS spectra are found to be consistent with the values obtained from simulated I–V characteristics. Thus, these surface analytical tools, XPS/UPS and C-AFM/SKPM, that do not require any sample preparation are found to be powerful characterization techniques to analyze the dopant incorporation and carrier density in homogeneously doped NWs.

Fabrication of TiO2 Spheres and a Visible Light Active α-Fe2O3/TiO2-Rutile/TiO2-Anatase Heterogeneous Photocatalyst from Natural Ilmenite

“…The binding energy of Fe 2p 3/2 of pure α-Fe 2 O 3 is reported to be at 709.32 eV . The binding energy of Fe 2p 3/2 in TF-800 appeared at 711.95 eV, suggesting a decrease in the electron concentration at α-Fe 2 O 3 of TF-800 . The degree of delocalization and/or electronic coupling between TiO 2 empty electronic states can be demonstrated by proving that α-Fe 2 O 3 impacts electronic states around the Fermi level .…”

“…20 The binding energy of Fe 2p 3/2 in TF-800 appeared at 711.95 eV, suggesting a decrease in the electron concentration at α-Fe 2 O 3 of TF-800. 112 The degree of delocalization and/or electronic coupling between TiO 2 empty electronic states can be demonstrated by proving that α-Fe 2 O 3 impacts electronic states around the Fermi level. 113 As a result of the low electron density at iron-based species, photogenerated electrons are readily taken up by TiO 2 , resulting in the production of • O 2 – , which degrades MB as proposed by the mechanism.…”

CoFe alloy nanoparticles encapsulated in a 3D honeycomb-like N-doped graphitic carbon framework for photocatalytic CO2reduction

“…The work function ( Φ ) was extracted from the difference between the energy of the UV photons and the secondary electron cutoff (high binding energy 21.2 eV). 64 The calculated work functions ( Φ ) of N-GC and CoFe-800 are 4.86 and 4.99 eV, respectively. Therefore, the Fermi levels of N-GC-800 and CoFe-800 are −4.86 and −4.99 eV.…”

Cathodoluminescence mapping of electron concentration in MBE-grown GaAs:Te nanowires

“…Previous studies have already demonstrated the successful incorporation and activation of Te dopants in GaAs NWs using a combination of atom probe tomography, Raman spectroscopy, photoluminescence, secondary ion mass spectrometry, electron holography, single NW transport measurement and Kelvin probe force microscopy [19][20][21][22]. Electron concentrations up to the 10 19 cm −3 range without compensation have been reported by Orr et al [21], while more recently concentrations between 2 and 4 x 10 19 cm −3 have also been reported for Te-doped GaAsSb NWs, using for the first time a combination of XPS/UPS and C-AFM/KPFM [23]. From the XPS spectra, signs of complex dopant distribution in the Te-doped GaAsSb NWs were observed but the latter could not be quantified using the above characterization techniques.…”