“…However, both values follow the same trends like the peak position and the relative SEAL area: if a reduced downward band bending is observed and consequently less free electrons exist in the surface‐near accumulation region, the core level and valence band spectra become more narrow. The phenomenon of an increased peak asymmetry for higher surface electron concentration was already observed for indium‐tin‐oxide and indium nitride . This effect can be either explained by excitation of plasmon inducing a reduction of the photoelectron energy or by the formation of screened and unscreened final states in the photoemission process, which are dependent on the conduction electron density .…”
Section: Resultsmentioning
confidence: 64%
“…The phenomenon of an increased peak asymmetry for higher surface electron concentration was already observed for indium-tin-oxide and indium nitride. [35][36][37] This effect can be either explained by excitation of plasmon inducing a reduction of the photoelectron energy or by the formation of screened and unscreened final states in the photoemission process, which are dependent on the conduction electron density. [38] Independent on the physical description, in both cases a stronger asymmetry at the high binding energy side of the spectra is induced by an enhanced electron concentration.…”
Section: Sequential Interaction Of Ozone/oxygen and Watermentioning
The interaction of ozone, oxygen, and water molecules with the (111) surface of indium oxide grown by plasma‐assisted molecular beam epitaxy is investigated. In order to characterize the adsorption and charge transfer mechanisms taking place at ozone‐sensitive In2O3 films and to determine the effect of humidity, we study the chemical and electronic surface properties using photoelectron spectroscopy. Clean surfaces are prepared by vacuum annealing and subsequently exposed to O3, O2, or H2O in serial adsorption sequences. After ozone and oxygen interaction, the same adsorbate species are detected and both molecules reduce the surface electron density, resulting in a decrease of film conductance. However, the quantitative changes of adsorbate coverage, band bending, surface electron concentration, and work function indicate a much higher reactivity of the surface with ozone. In contrast, if the surface is exposed to water, the resulting adsorbates have a different spectroscopic signature and do not significantly alter surface band bending and electron concentration. The effects of ozone/oxygen interaction are weakened if the surface was pre‐exposed to water. These results indicate that water adsorbates occupy surface sites that are consequently not available for ozone interaction and that humidity influences the device sensitivity but not its selectivity toward oxidizing gases.
“…However, both values follow the same trends like the peak position and the relative SEAL area: if a reduced downward band bending is observed and consequently less free electrons exist in the surface‐near accumulation region, the core level and valence band spectra become more narrow. The phenomenon of an increased peak asymmetry for higher surface electron concentration was already observed for indium‐tin‐oxide and indium nitride . This effect can be either explained by excitation of plasmon inducing a reduction of the photoelectron energy or by the formation of screened and unscreened final states in the photoemission process, which are dependent on the conduction electron density .…”
Section: Resultsmentioning
confidence: 64%
“…The phenomenon of an increased peak asymmetry for higher surface electron concentration was already observed for indium-tin-oxide and indium nitride. [35][36][37] This effect can be either explained by excitation of plasmon inducing a reduction of the photoelectron energy or by the formation of screened and unscreened final states in the photoemission process, which are dependent on the conduction electron density. [38] Independent on the physical description, in both cases a stronger asymmetry at the high binding energy side of the spectra is induced by an enhanced electron concentration.…”
Section: Sequential Interaction Of Ozone/oxygen and Watermentioning
The interaction of ozone, oxygen, and water molecules with the (111) surface of indium oxide grown by plasma‐assisted molecular beam epitaxy is investigated. In order to characterize the adsorption and charge transfer mechanisms taking place at ozone‐sensitive In2O3 films and to determine the effect of humidity, we study the chemical and electronic surface properties using photoelectron spectroscopy. Clean surfaces are prepared by vacuum annealing and subsequently exposed to O3, O2, or H2O in serial adsorption sequences. After ozone and oxygen interaction, the same adsorbate species are detected and both molecules reduce the surface electron density, resulting in a decrease of film conductance. However, the quantitative changes of adsorbate coverage, band bending, surface electron concentration, and work function indicate a much higher reactivity of the surface with ozone. In contrast, if the surface is exposed to water, the resulting adsorbates have a different spectroscopic signature and do not significantly alter surface band bending and electron concentration. The effects of ozone/oxygen interaction are weakened if the surface was pre‐exposed to water. These results indicate that water adsorbates occupy surface sites that are consequently not available for ozone interaction and that humidity influences the device sensitivity but not its selectivity toward oxidizing gases.
“…[12][13][14][15] The charge-neutrality level (CNL) in InN, is well above the conduction band minimum, resulting in intrinsic n-type charge carrier doping of the "as grown" material. This leads to surface band bending and the formation of a particularly prominent electron accumulation layer.…”
The unique electronic
band structure of indium nitride InN, part
of the industrially significant III–N class of semiconductors,
offers charge transport properties with great application potential
due to its robust n-type conductivity. Here, we explore
the water sensing mechanism of InN thin films. Using angle-resolved
photoemission spectroscopy, core level spectroscopy, and theory, we
derive the charge carrier density and electrical potential of a two-dimensional
electron gas, 2DEG, at the InN surface and monitor its electronic
properties upon in situ modulation of adsorbed water.
An electric dipole layer formed by water molecules raises the surface
potential and accumulates charge in the 2DEG, enhancing surface conductivity.
Our intuitive model provides a novel route toward understanding the
water sensing mechanism in InN and, more generally, for understanding
sensing material systems beyond InN.
“…The quantized conduction sub-band with n = 1 has a smaller binding energy than that reported in previous work 16 where CdO films with the thickness of 380 nm were grown on r -plane sapphire using metal-organic vapor phase epitaxy and cleaned in UHV by an annealing at 600 °C, that is higher than our annealing temperature of 300 °C. This could affect the concentration of electrically active surface adsorbates which, as has been shown in refs 28,29 , are important factors determining the surface band bending.Figure 7( a ) ARPES intensity map at near Fermi level of CdO (x = 1.0) measured at hν = 30 eV. The conduction sub-band dispersion determined from the peak fitting to the MCD and EDC are plotted by solid circles.…”
Section: Resultsmentioning
confidence: 87%
“…These localized states contribute to the surface electric current. Recently, it has been reported that sub-band energies and corresponding surface carrier accumulation are greatly increased by electric dipole layer with the adsorption of molecules on the surface of degenerated semiconductors 28,29 . Thus, both parental bulk-carrier-density and surface carrier distribution that greatly depends on the environment should be carefully taken into account for the exact evaluation of transport properties.…”
Three-dimensional band structure of rock-salt (rs) Cd
x
Zn
1
−
x
O (
x
= 1.0, 0.83, and 0.60) have been determined by angle-resolved photoemission spectroscopy (ARPES) using synchrotron radiation. Valence-band features shift to higher binding energy with Zn content, while the conduction band position does not depend strongly on Zn content. An increase of the indirect band gap with Zn-doping is larger than that of the direct band gap, reflecting a weaker hybridization between Zn 3
d
and O 2
p
than that between Cd 4
d
and O 2
p
. Two-dimensional electronic states due to the quantization along surface normal direction are formed in the surface accumulation layer and show non-parabolic dispersions. Binding energy of the quantized two-dimensional state is well reproduced using an accumulation potential with the observed surface band bending and the characteristic width of about 30 Å.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
