Intrinsic defects and mid-gap states in
quasi-one-dimensional indium telluride

Meryem Bouaziz, Aymen Mahmoudi, Geoffroy Kremer, Julien Chaste, César González, Yannick J. Dappe, François Bertran, Patrick Le Fèvre, Marco Pala, Fabrice Oehler, et al.

► To cite this version:

Meryem Bouaziz, Aymen Mahmoudi, Geoffroy Kremer, Julien Chaste, César González, et al. Intrinsic defects and mid-gap states in quasi-one-dimensional indium telluride. Physical Review Research, 2023, 5 (3), pp.033152. 10.1103/PhysRevResearch.5.033152. hal-04190986v2

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<figure><img src="image_1.png" /></figure>
Intrinsic defects and mid-gap states in quasi-one-dimensional indium telluride

Meryem Bouaziz,<sup>1,*</sup> Aymen Mahmoudi<sup>1</sup>, Geoffroy Kremer,<sup>1,2</sup> Julien Chaste,<sup>1</sup> César González<sup>1,3,4</sup>

Yannick J. Dappe,<sup>5</sup> François Bertran,<sup>6</sup> Patrick Le Fèvre<sup>6</sup>, Marco Pala<sup>1</sup>, Fabrice Oehler<sup>1</sup>

Jean-Christophe Girard<sup>1</sup>, and Abdelkarim Ouerghi<sup>1,†</sup>

<sup>1</sup>Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies, 91120 Palaiseau, Paris, France

<sup>2</sup>Institut Jean Lamour, UMR 7198, CNRS-Université de Lorraine, Campus ARTEM, 2 allée André Guinier, BP 50840, 54011 Nancy, France

<sup>3</sup>Departamento de Física de Materiales, Universidad Complutense de Madrid, 28040 Madrid, Spain

<sup>4</sup>Instituto de Magnetismo Aplicado UCM-ADIF, E-28232 Las Rozas de Madrid, Spain

<sup>5</sup>SPEC, CEA, CNRS, Université Paris-Saclay, CEA Saclay, Gif-sur-Yvette Cedex 91191, France

<sup>6</sup>Synchrotron SOLEIL, L'Orme des Merisiers, Départementale 128, F-91190 Saint-Aubin, France

<figure><img src="image_2.png" /></figure>

(Received 20 February 2023; revised 19 May 2023; accepted 24 May 2023; published 5 September 2023)

Recently, intriguing physical properties have been unraveled in anisotropic semiconductors in which the in-plane electronic band structure anisotropy often originates from the low crystallographic symmetry. The atomic chain is the ultimate limit in material downscaling for electronics—a frontier for establishing an entirely new field of one-dimensional quantum materials. Electronic and structural properties of chain-like InTe are essential for a better understanding of device applications such as thermoelectrics. Here, we use scanning tunneling microscopy/scanning tunneling spectroscopy (STS) measurements and density functional theory (DFT) calculations to image the in-plane structural anisotropy directly in tetragonal InTe. As results, we report the direct observation of one-dimensional In¹⁺ chains in InTe. We demonstrate that InTe exhibits a bandgap of about 0.40 ± 0.02 eV located at the *M* point of the Brillouin zone. Additionally, line defects are observed in our sample and were attributed to In¹⁺ chain vacancy along the *c*-axis—a general feature in many other TiSe₂-like compounds. Our STS and DFT results prove that the presence of In¹⁺ induces a localized gap state, located near the valence band maximum. This acceptor state is responsible for the high intrinsic p-type doping of InTe that we also confirm using angle-resolved photoemission spectroscopy.

DOI: 10.1103/PhysRevResearch.5.033152

# I. INTRODUCTION

In the vast family of two-dimensional (2D) van der Waals materials [1], many iconic compounds such as graphene, boron nitride, or transition metal dichalcogenide (*MX*₂, with *M* being a transition metal and *X* a chalcogen element [2–4]) display a hexagonal crystal symmetry. Consequently, their out-of-plane (*z* direction) properties (e.g., electronic, mechanic, thermal) are usually very different from their in-plane counterpart (*xy* directions), but the material is essentially isotropic in the *xy* plane due to the six-fold crystal symmetry [5]. In addition to those 2D in-plane isotropic compounds, quasi-one-dimensional (quasi-1D) crystals are a class of anisotropic materials wherein atoms are arranged within the *xy* plane to form 1D-like structures, most often covalent chains, which extend along a particular lattice direction [6,7]. Some examples of these quasi-1D crystals include black phosphorus, SnSe, GaTe, InTe, and ReS₂ [8–12], which have attracted considerable attention owing to their in-plane

anisotropic physical properties, including high electronic conductivity, thermal conductivity, and exciton recombination occurring only for a given lattice direction [10]. Such particular properties have prompted unconventional applications, such as polarization-sensitive photodetectors and thermoelectric devices [12,13]. As a consequence of their quasi-1D crystal structure, the electronic band structure of these materials typically combines the 2D-like thickness-dependent character along the *z* direction with inequivalent electronic dispersions along the *x* and *y* directions in the plane, bridging the gap between 2D and 1D materials such as nanowires, nanotubes, and other systems with a high geometrical aspect ratio [7].

Monotelluride compounds such as InTe and GaTe typically show a quasi-1D crystal structure, with weak out-of-plane bonding and anisotropic in-plane character [11]. However their environmental stability under ambient conditions is of concern, since other tellurium-based 2D materials such as MoTe₂ and WTe₂ are known to suffer rapidly from oxygen or moisture exposure [14,15]. As a consequence, the surface investigation of pristine InTe requires specific conditions, which we propose here to conduct using scanning tunneling microscopy (STM) operating in ultra-high-vacuum (UHV) conditions. STM has long been used to image the electronic structure of individual point defects in conductors, semiconductors, and ultrathin films [16]. Specific defects in InTe such as indium vacancies are known to form in the bulk and to

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

<footnote>*meryem.bouaziz@universite-paris-saclay.fr</footnote>

<footnote>†abdelkarim.ouerghi@universite-paris-saclay.fr</footnote>
<figure><img src="image_3.png" /><figcaption>FIG. 1. Crystallographic and μ-Raman analysis of InTe. (a) Crystal structure of tetragonal InTe. In$^{1+}$, In$^{3+}$, and tellurium atoms are represented as green, blue, and pink spheres, respectively. The preferred 110 cleaving plane is indicated in light brown. The unit cell in marked by a black line. (b) Theoretical InTe (110) surface, exposing the In$^{1+}$ atoms and the corresponding surface cell parameter. (c) Room-temperature μ-Raman spectra acquired from a different zone from a cleaved InTe (110) surface showing the three expected Raman lines: $E_g$ at 48 cm$^{-1}$ and 138 cm$^{-1}$, and the $A_{1g}$ at 126 cm$^{-1}$.</figcaption></figure>

affect thermoelectric properties [17,18]. In this context, the experimental surface characterization of the quasi-1D InTe surface and its associated defects is of interest, but is not yet reported in the literature.

Here we investigate the surface and electronic properties of InTe using STM and angle-resolved photoemission spectroscopy (ARPES). The crystalline nature of tetragonal InTe is first confirmed by STM, micro (μ)-Raman spectroscopy, and ARPES, with the expected natural cleavage plane corresponding to the (110) surface [10]. The ARPES data present a sharp band structure, indicative of the quality of the InTe crystal, but also a substantial p-type character. Further investigations by scanning tunneling spectroscopy (STS) identify specific defective regions, which impose particular electronic properties on InTe with respect to other defect-free areas. Comparison with the theoretical band structure and local density of state (LDOS) calculations using density functional theory (DFT) confirms the existence of in-gap states close to the valence band maximum (VBM), at the origin of the observed p-type character of InTe.

## II. EXPERIMENTAL DETAILS

### A. Photoemission spectroscopy

ARPES experiments were performed at the CASSIOPEE beamline of the SOLEIL synchrotron light source. The

CASSIOPEE beamline is equipped with a Scienta R4000 hemispherical electron analyzer whose angular acceptance is ±15° (Scienta Wide Angle Lens). The valence band data were calibrated with respect to the Fermi level. High-quality samples from the “2D semiconductors” company were cleaved in UHV at a base pressure better than $1 \times 10^{-10}$ mbar. The Fermi level was determined by fitting the leading edge of the gold crystal at the same photon energies and under the same experimental conditions. The experiment was performed at T = 30 K. The incident photon beam was focused into a 50-μm spot (diameter) on the sample surface. All ARPES measurements were performed with a linear horizontal polarization.

### B. Scanning tunneling microscopy

STM experiments are performed at 77 K using an LT-STM (Scienta-Omicron). The sample is prepared in the same conditions as ARPES measurements, cleaved at a base pressure better than $1 \times 10^{-10}$ mbar and transferred immediately in the precooled STM head. STM images are acquired in the constant current mode.

### C. μ-Raman measurements

The μ-Raman measurements were conducted at room temperature using a commercial confocal Horiba micro-Raman microscope with a ×100 objective and a 532-nm laser excita-
<figure><img src="image_4.png" /><figcaption>FIG. 2. (a) Projected Brillouin zone of InTe along the 110 axis. b) Isoenergetic contour around the *M* point at -0.5 eV showing the 1D character of InTe (*h*ν = 50 eV). (c) and (d) Experimental ARPES dispersion of InTe along the *MXM* direction obtained with a photon energy of *h*ν = 50 eV and 118 eV, respectively. (e) ARPES data (*h*ν = 50 eV) superposed with theoretical DFT results computed with the HSE06 functional. The DFT bands are shifted to account for the Fermi-level position for the ARPES image.</figcaption></figure>

tion. The laser beam was focused onto a small spot (diameter, ~1 µm) on the sample.

### III. RESULTS AND DISCUSSION

Bulk InTe is a tetragonal semiconductor that crystallizes in the TISe structure under ambient conditions [19]. It is best described by the tetragonal space group *I*4/mcm, with the unit cell [Fig. 1(a), black line] being a right-angled cuboid with parameters *a* = 8.444 Å in the (100) and (010) directions while *a* ≠ *c* = 7.136 Å along the [001] axis [17]. As-grown bulk InTe typically exhibits a p-type character [10,20]. While tellurium atoms solely occupy one crystallographic site (8h), indium atoms are distributed equally over two independent crystallographic sites—named hereafter In¹⁺ and In³⁺, respectively. The In³⁺ ions are tetrahedrally coordinated with tellurium atoms, forming covalent infinite edge-sharing tetrahedra along the *c* direction. Perpendicularly, along the [100] and [010] directions, those infinite (InTe₂)⁻ covalent chains are weakly bonded to each other and intercalated by In¹⁺ ions. These In¹⁺ ions are actually surrounded by eight tellurium atoms in a tetragonal antiprismatic coordination, but show large atomic displacement values along the *c* direction, moving in a tunnel-like configuration between the covalently bound (InTe₂)⁻ chains [10]. Due to the weak interactions between (InTe₂)⁻ chains, the crystal tends to cleave along the (110) planes [20] [Fig. 1(a), light brown], cutting through the mobile In¹⁺ positions. The exposed (110) surface

shows a rectangular symmetry with parameter *a*√2 and *c* (Figure 1(b)). While the exposed In¹⁺ atoms form a regular lattice of smaller parameter *a*√2/2 and *c*/2, the underlying tellurium atoms are positioned so that adjacent (InTe₂)⁻ along [−110] chains are shifted by *c*/2 along [001] [see Fig. 1(a) and (b), (220) light-green plane], which requires boxing the entire surface cell. Representative Raman spectra acquired in three different zones (room temperature, 532-nm laser) from a freshly cleaved commercial InTe sample (2D Semiconductors) are shown in Fig. 1(c). All spectra expose identical Raman features with the same magnitude. The *E*<sub>*g*</sub> (48 cm⁻¹, 138 cm⁻¹), *B*<sub>1g</sub> (86 cm⁻¹), and *A*<sub>1g</sub> (126 cm⁻¹) single modes are observed with frequencies that are in agreement with the literature on ambient tetragonal InTe [19,21], confirming the expected crystal structure and quality of our sample.

To resolve the previously described electronic properties of InTe, we have performed low-temperature ARPES measurements (30 K). In Fig. 2(a), we show the projected first Brillouin zone of InTe for the (110) surface. It exposes two inequivalent directions in reciprocal space that are perpendicular: *MXM*, which is aligned with the real-space direction [−110] [i.e., across the (InTe₂)⁻ chains], and *MZM* along [001] [i.e., along the (InTe₂)⁻ chains], as expected from the anisotropic real-space symmetry [Figs. 1(a) and 1(b)]. In Fig. 2(b), we present the isoenergetic contours obtained at the *M* point (binding energy = −0.5 eV). The elliptical valley image is the result of anisotropy electronic properties of InTe.
<figure><img src="image_5.png" /><figcaption>FIG. 3. Structural and electronic properties of InTe. (a) Large-scale STM image at 77 K of the UHV-cleaved surface of InTe revealing the oriented step edges on this surface ($V_{bias} = -0.5$ eV, $I_{tunneling} = 100$ pA). (b) and (c) Zoomed-in STM images, obtained with the same parameters, showing more linear features. (d) The corresponding FFT indicating the $a\sqrt{2} \times c$ periodicity of the InTe (110) surface. (e) The differential conductance ($dI/dV$) spectrum as a function of the bias voltage (red and blue curves), showing that the energy bandgap is ~0.40 ± 0.02 eV. Total and partial electronic densities of states near the top of the valence band and the bottom of the conduction band of InTe (dashed black curve).</figcaption></figure>

In Fig. 2(c) and (d), we report the experimental ARPES dispersion of the (110) InTe surface acquired along the *MXM* direction using a photon energy of 50 and 118 eV (surface and bulk sensitivity). The topmost part of the valence band is characterized by hole-like bands centered at the *M* point. The VBM at the *M* point of the Brillouin zone is mostly formed by *p* and *s* orbitals of tellurium and indium respectively, while at the *X* point the band is mostly composed by *p* orbitals of tellurium. We observe that the VBM is located at the Fermi level for the two-photon energy. This confirms the high *p*-type character of our InTe (110) bulk. Comparison with DFT calculations using the HSE06 functional [Fig. 2(e)] shows a good agreement. Considering the electronic bandgap of InTe calculated by Heyd-Scuseria-Ernzerhof, the VBM position indicates a *p*-type doping of InTe. This result confirms the strong *p*-type character of our InTe, in agreement with literature results on bulk InTe¹⁰.

In order to determine the physical origin of the observed, strong *p*-type doping, we carried out a combined STM/STS study of the InTe (110) surface [7,22]. Figure 3(a) shows a large-scale topographic STM image of the UHV-cleaved surface of InTe, revealing wide terraces separated by high-density

step edges and extended line defects aligned exclusively along a single in-plane direction, close to the vertical axis in Fig. 3(a). In zoomed-in STM images [Figs. 3(b) and 3(c)], we notice the ordered flat regions are better resolved and show finer features aligned along the same direction than the step edges. The corresponding fast Fourier transform [shown in Fig. 3(d)] reveals a clear rectangular symmetry, with the spacing along the vertical direction being close to that of the *c*-axis (8.0 Å) and the horizontal matching that of $a\sqrt{2} = (11.9Å)$. Comparison with the expected InTe (110) surface [Fig. 1(b)] confirms the surface orientation and cleavage plane, and determines the long axis of the step edges [large scale, Fig. 3(a)] and linear atomic features [small scale, Figs. 3(b) and 3(c)] to be the crystal *c*-axis. The absence of any other feature indicates that our InTe crystal is fully monocrystalline, without any rotational disorder, twinning domains, pits, or antiphase domain boundaries. The STM characterization of the InTe (110) surface strongly reflects the expected anisotropy of the InTe (110) and allows the direct imaging of 1D-like electronic features along the (in-plane) *c*-axis [10,19]. Figure 3(c) clearly shows that the InTe layer is incomplete, i.e., $In^{1+}$ and $(InTe_2)^-$ ions are missing, which leads to the appearance of dark lines
<figure><img src="image_6.png" /><figcaption>FIG. 4. Experimental and simulated STM images. (a) Experimental STM image of a fully In¹⁺ terminated InTe (110) surface acquired using *U* = 0.2 V and *I* = 100 pA. (b) and (c) Simulated STM image of defect-free InTe and InTe with In⁺ defects taken at constant-height mode with *U* = -1 V and an STM tip 4.2 Å above the averaged InTe (110) surface. WSxM software was used for visualizing the image [30].</figcaption></figure>

corresponding to holes. This suggests that single-atom vacancy defects on InTe can be formed. The density of In¹⁺ vacancies is estimated to be about 20% to 40% of the area.

To investigate the electronic bandgap, complementary STS measurement at 77 K in defect-free (red spectrum) and defective (blue spectrum) areas, coupled with DFT calculations of LDOS [23] are presented in Fig. 3(e). The experimental differential conductance (dI/dV) spectroscopy versus bias voltage spectra is compared to the LDOS calculated by DFT. The

theoretical LDOS of the InTe is very sharp at the top of the valence band and near the conduction band minimum, as well as for the experimental STS. The conduction band minimum is located at 0.28 ± 0.02 eV above the Fermi level, for both experimental spectra as well as for the calculated LDOS. However, a difference on the valence band side is noticed. The VBM is located at 0.12 ± 0.02 eV below the Fermi level (i.e., zero bias on the *d*I/*d*V spectra) in the defect-free area, while it is located near *E*<sub>F</sub> for the spectrum measured on a defect. By comparing the two STS spectra (red and blue tank), we can see a difference in the VBM region. This difference can be associated with localized states in the gap of the sample near the VBM. The intrinsic electron quasiparticle bandgap is estimated at about *E* = 0.40 ± 0.02 eV. This value is of the same range as the one obtained with the DFT (≈0.41 eV). The uncertainty in bandgap is the result of the lateral band-edge variations. The Fermi energy, corresponding to the zero bias in the *d*I/*d*V spectrum, is positioned near the VBM. As such, it suggests the presence of intrinsic charged defects in our specimens and a p-type doping, which we could relate to lattice vacancies or antisites responsible for p-doping in other 2D materials [24]. Still, the p-type character of our InTe (110) surface observed by STS agrees with our ARPES measurements.

In Fig. 4(a), we present a STM image of a particular area (defect free). We measure a spatial periodicity of *a*√2/2 × *c*/2 in the perpendicular direction, which is consistent with the

<figure><img src="image_7.png" /><figcaption>FIG. 5. Atomistic defects of the InTe (110) surface. (a) Atomically resolved STM topography (26 × 26 Å², *U* = -0.5 V, *I* = 30 pA). (b) Line profile across the chain. (c) Regular In¹⁺ vacancy arrangement in a rectangular lattice. (d) Linear arrangement of In¹⁺ vacancy forming an extended segment along the in-plane *c*-axis.</figcaption></figure>
lattice parameters of the structure [Fig. 1(b)]. From the struc-
tural model, we attributed that the imaged bright spots to
the In¹⁺. To verify our hypothesis, we have performed DFT
calculations using the DFT local orbital molecular-dynamics
code as implemented in Fireball [25–28]. We have optimized
a 1 × 1 unit cell of fully In¹⁺ terminated (defect free) InTe and
InTe with In⁺ defects until the forces went below 0.1 eV Å⁻¹.
A set of 8 × 8 × 1 k-points has been used for both struc-
tural optimization and DOS calculations. STM simulations
have been performed within a Keldysh-Green function for-
malism as described in Ref. [29] On the other hand, the tip
is modeled by a W-pyramid of five atoms coupled to four
layers of W(100) with a 5 × 5 periodicity. WSxM software
has been used for image visualization [30]. In Figs. 4(b) and
4(c), we present two simulated STM images (InTe defect
free and InTe with In⁺ defects), constructed with the same
parameters as our STM experimental conditions. We observe
a good match between the experimental and simulated STM
image of defect-free InTe (110) [Figs. 4(a) and 4(b)]. Based
on DFT calculations, we confirm the direct observation of
one-dimensional In¹⁺ chains in an InTe [Fig. 4(a)]. The su-
perposed crystal lattice from DFT [Fig. 4(b), insert] confirms
that the observed protrusions localize close to the In¹⁺ atomic
positions.

For the defective InTe, the calculated STM image
[Fig. 4(c)] shows the In¹⁺ vacancy as a depression, which
is similar to the experimental observation [Fig. 3(c)]. The
topographic signature of these defects is imaged using STM,
showing the In¹⁺ vacancies as depressions on the InTe
surface—notably, extended vacancy lines along the crystal
c-axis. If we refer to Fig. 3(c), we now interpret the line
defect to be In¹⁺ defective. Our STM/STS and ARPES results
thus demonstrate such In¹⁺ vacancies are responsible for the
p-type character of InTe and, more generally, are a typical
feature of TiSe-like materials [10].

We now turn to the detailed investigation of the InTe (110)
with In¹⁺ defects in order to study the atomic structure of the
observed 1D line features. Figure 5(a) shows an atomically
resolved STM image of the InTe (110) surface. The crystal
c-axis is vertical, and the corresponding chain-like features are
now obvious. However, we note that each 1D chain presents
a slightly different structure along its axis than its neighbors,
alternating short, long protrusions or gaps. The height profile
perpendicular to the chains [Fig. 5(a), blue line] is shown
in Fig. 5(b). The oscillation period is a√2/2 (~6 Å) and
the depth is about 1 Å. This vertical distance corresponds
to the vertical distance between the top In¹⁺ atoms and the
underlying In³⁺ atoms. The lateral period also matches the
expected In¹⁺ position, with a spacing of a√2/2 [Fig. 1(b)]
along the -110 direction. Given that the InTe (110) surface
is obtained by mechanical cleaving through the In¹⁺ (110)
plane, we suggest some vacancy in the exposed In¹⁺ layer
at the top surface. In Fig. 5(c) (left), we investigate a small
regular array characterized by a lateral length of a√2/2, but
with a double vertical period (7 Å) equal to cell parameter
c. Following our hypothesis, this situation corresponds to a
regular reconstruction of the surface with half of the In¹⁺

atoms missing [Fig. 5(c), right]. Another variant is presented
Fig. 5(d) (left), in which a typical extended 1D defect is shown
and which we interpret as In¹⁺ vacancies aligned along the
c-axis [Fig. 5(d), right]. This surface model with mobile In¹⁺
vacancies is also compatible with the overall picture shown
in Fig. 5(a). This spatial distribution of In¹⁺ vacancies is
random and creates various combinations of regular arrays
(a√2/2 × c, ~40% In¹⁺ vacancies), vacancy lines, or less
ordered arrangements.

IV. CONCLUSION

In summary, we have combined complementary techniques
to investigate the structural and electronic properties of the
cleaved surface of quasi-1D InTe. Our combined DFT and
STM study confirms the (110) preferential cleaving plane
and reveals various surface organization of In¹⁺ vacancies,
sometimes arranged in a regular array but mostly in extended
segments along the in-plane c-axis. These In¹⁺ vacancies are
the dominant defects in InTe, and the STS results indicate
that they are responsible for the strong p-type doping of InTe,
as also observed using ARPES. Further investigation of these
In¹⁺ vacancies offers insight into alternative doping strategies,
possibly by substitution, to obtain opposite n-type electrical
conduction while maintaining the inherent, strong anisotropy
of InTe.

ACKNOWLEDGMENTS

We acknowledge the financial support by MagicValley
(Grant No. ANR-18-CE24-0007) and Graskop (Grant No.
ANR-19-CE09-0026), 2D-on-Demand (Grant No. ANR-20-
CE09-0026), and MixDferro (Grant No. ANR-21-CE09-
0029), the French technological network RENATECH. This
work is also supported by a public grant overseen by the
French National Research Agency (ANR) as part of the “In-
vestissements d’Avenir” program (Labex NanoSaclay, Grant
No. ANR-10-LABX-0035) and by the French technologi-
cal network RENATECH. C.G. thankfully acknowledges the
computer resources at Altamira, the technical support pro-
vided by the Physics Institute of Cantabria (IFCA) of the
University of Cantabria (Project No. FI-2022-3-0021), and
the financial support by the Spanish Science and Innovation
Ministry (Project No. PID2021-123112OB-C21).

The authors declare no competing interests.

APPENDIX

Figure 6 presents the ARPES dispersion of the (110) InTe
surface acquired along the MXM direction using a photon
energy of 84 eV.

The energy distribution curves (EDCs) of the valence band,
measured with a photon energy of 50 and 118 eV, are shown
in Fig. 7 (green and red lines). On the same graph, the Fermi
edge of a clean gold sample measured in the same experimen-
tal conditions is presented (blue line). The zero of the binding
energy (i.e., the Fermi level) was taken at the leading edge of
this gold sample.
<figure><img src="image_8.png" /><figcaption>FIG. 6. Experimental ARPES dispersion of InTe along the MXM direction obtained with a photon energy of hν = 84 eV.</figcaption></figure>

<figure><img src="image_9.png" /><figcaption>FIG. 7. EDCs extracted from ARPES measurements at 50 eV (green line) and 118 eV (red line). The blue curve is the Fermi edge of a clean gold sample measured in the same experimental conditions.</figcaption></figure>

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