Band gap and electron transport in epitaxial cubic 
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McGahay, Mary E.; Wang, Baiwei; Shi, Jian; Gall, Daniel

doi:10.1103/physrevb.101.205206

Cited by 12 publications

(3 citation statements)

References 72 publications

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“…A further increase in the Mg content leads to a considerably larger resistivity, with ρ 5K = 196 μΩ•cm and ρ 300K = 203 μΩ•cm for Ti 0.61 Mg 0.39 N, as shown in Figure 5b. The data indicate a resistivity minimum at 60 K, which is attributed to weak localization caused by the random occupation of cation sites and/or the random distribution of nitrogen vacancies, similar to what has been reported for other transition metal nitrides including CrN(001), 66 TaN x (001), 67 HfN x (001), 68 Cr 1−x Al x N(001), 46 Sc 1−x Ti x N(001), 30 and Ti 1−x W x N(001). 26 The finite low-temperature resistivity indicates that the Fermi level for Ti 0.61 Mg 0.39 N is above the conduction edge and, as expected from simple electron counting, is well within the conduction d band such that electron transport is best described by a weak Anderson localization.…”

Section: ■ Results and Discussionsupporting

confidence: 79%

“…Second, (ii) n is obtained from the measured R , keeping k constant. Third, (iii) α and the corresponding k are corrected using the measured T , accounting for multiple coherent reflections at the air–layer and layer–MgO interfaces and the incoherent reflection at the substrate back surface and the absorption in the substrate, ,, using n and k for the Ti 1– x Mg x N layer from the previous iteration step and the measured optical constants for MgO from a bare substrate. Subsequently, steps (ii) and (iii) are repeated until n and k are converged.…”

Section: Methodsmentioning

confidence: 99%

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Tunable Infrared Plasmonic Properties of Epitaxial Ti_1–xMg_xN(001) Layers

Wang

Nawarat

Lewis

et al. 2021

ACS Appl. Mater. Interfaces

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Optical transmission and reflection spectra in combination with ellipsometry and transport measurements on epitaxial rocksalt structure Ti1–x Mg x N(001) layers with 0.00 ≤ x ≤ 0.49 are employed to explore their potential as refractory infrared plasmonic materials. A red shift in the reflection edge ℏωe from 2.0 to 0.8 eV and the corresponding unscreened plasma energy ℏωpu from 7.6 to 4.7 eV indicate a linear reduction in the free carrier density N with increasing x. However, nitrogen vacancies in Mg-rich samples act as donors, resulting in a minimum N = 1.6 × 1022 cm–3 for x = 0.49. Photoelectron valence band spectra confirm the diminishing conduction band density of states and indicate a 0.9 eV decrease in the Fermi level as x increases from 0 to 0.49. The dielectric function ε = ε1 + iε2 can be divided into a low-energy spectral region where intraband transitions result in large negative and positive ε1 and ε2, respectively, and a higher energy interband transition region with both ε1 and ε2 > 0. The screened plasma energy E ps that separates these two regions red-shifts from 2.6 to 1.3 eV for x = 0–0.39, indicating a tunable plasmonic activity that extends from the visible to the infrared (470–930 nm). Electron transport measurements indicate a metallic temperature coefficient of resistivity (TCR) for TiN-rich alloys with x ≤ 0.26 but weak carrier localization and a negative TCR <60 K for x = 0.39 and <300 K for x = 0.49, attributed to Mg alloying-induced disorder. The plasmonic quality factor Q is approximately an order of magnitude larger than what was previously reported for polycrystalline Ti1–x Mg x N, making Ti1–x Mg x N(001) layers competitive with Ti1–x Sc x N(001).

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Section: ■ Results and Discussionsupporting

confidence: 79%

Section: Methodsmentioning

confidence: 99%

Tunable Infrared Plasmonic Properties of Epitaxial Ti_1–xMg_xN(001) Layers

Wang

Nawarat

Lewis

et al. 2021

ACS Appl. Mater. Interfaces

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“…The bandgap formation is expected to be a result of Anderson localization, as observed in (Sc 1−x ,Ti x )N 29) and (Ti 1−x ,W x )N. 30) The introduction of Anderson localization into the Hubbard model can be explained by both localization due to strong electron-electron interactions and localization due to crystalline disorder. The semiconductor behavior of the (Cr 1−x ,V x )N solid solution is attributed to weak Anderson localization induced by random cation site transitions, 31,32) which are caused by VN substitution into CrN. The results for CrN in this experiment provide direct evidence for the metal-Mott insulator transition, which has previously been described only by the Hubbard model with the inclusion of the Anderson localization concept.…”

Section: Resultsmentioning

confidence: 50%

Structural and electrical properties of (Cr_1−x,V_x)N thin films epitaxially grown on MgO(001) substrates

Sawaya,

Bin Onn,

Suzuki

2024

Jpn. J. Appl. Phys.

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(Cr1−x,Vx)N thin films were grown on MgO(001) substrates by pulsed laser deposition, and their structural and electrical properties were characterized. The composition of the thin films was determined by Rutherford backscattering spectroscopy and X-ray fluorescence analysis. X-ray diffraction analyses confirmed that the thin film grown epitaxially and the lattice constant decreasing as x increased. The temperature dependence of the electrical resistivity of the (Cr1−x,Vx)N thin films indicated that CrN and VN exhibited metallic behavior, whereas (Cr1−x,Vx)N exhibited semiconductor behavior. The semiconductor behavior of (Cr1−x,Vx)N might be associated with Anderson localization in addition to Mott–Hubbard interactions.

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