Dual phase two-color emission observed in van der Waals GaTe planes

Muhimmah, Luthviyah Choirotul; Ho, Ching‐Hwa

doi:10.1016/j.apsusc.2020.148593

Cited by 20 publications

(29 citation statements)

References 53 publications

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“…The III-VI monochalcogenides GaSe 20,21 , GaS 22,23 , GaTe 24,25 , and InSe 26,27 are layered-type semiconductors with strong covalent bonds within each layer but a predominantly weakened van der Waals force 28 existing between the individual layers. The layered structure of III-VI monochalcogenides consists of an X-M-M-X assembly, where X is the chalcogen (Se, S, or Te) and M is the gallium or indium ion 18,28,29 . The absorption range of the bandgaps in III-VI monochalcogenides ranges from near-infrared (NIR) to ultraviolet 30 .…”

Section: Introductionmentioning

confidence: 99%

“…The unit cell of GaTe can consist of two layers. In monoclinic GaTe (M-GaTe), two-thirds of the Ga-Ga dimers are oriented perpendicular to the layer plane and the directions of the remaining one-third of Ga-Ga dimers are oriented nearly parallel to the layer plane 24,29,31 . Although M-GaTe is the main phase of gallium telluride, a metastable hexagonal (H) phase also exists in the compound at all thicknesses 25,29,30 .…”

Section: Introductionmentioning

confidence: 99%

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Near-infrared to red-light emission and carrier dynamics in full series multilayer GaTe1−xSex (0≤x≤1) with structural evolution

Muhimmah

Peng

et al. 2023

npj 2D Mater Appl

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Two-dimensional layered gallium monochalcogenide (GaX, where X = S, Se, Te) semiconductors possess great potential for use in optoelectronic and photonic applications, owing to their direct band edge. In this work, the structural and optical properties of full-series multilayer GaTe1−xSex for x = 0 to x = 1 are examined. The experimental results show that the whole series of GaTe1−xSex layers may contain one hexagonal (H) phase from GaTe to GaSe, whereas the monoclinic (M) phase predominates at 0 ≤ x ≤ 0.4. For x ≥ 0.5, the H-phase dominates the GaTe1−xSex series. The micro-photoluminescence (μPL) results indicate that the photon emission energy of M-phase GaTe1−xSex increases as the Se content increases from 1.652 eV (M-GaTe) to 1.779 eV (M-GaTe0.6Se0.4), whereas that of H-phase GaTe1−xSex decreases from 1.998 eV (H-GaSe) to 1.588 eV (H-GaTe) in the red to near-infrared (NIR) region. Micro-time-resolved photoluminescence (TRPL) and area-fluorescence lifetime mapping (AFLM) of the few-layer GaTe1−xSex series indicates that the decay lifetime of the band-edge emission of the M phase is faster than that of the H phase in the mixed alloys of layered GaTe1−xSex (0 ≤ x ≤ 0.4). On the other hand, for H-phase GaTe1−xSex, the decay lifetime of the band-edge emission also increases as the Se content increases, owing to the surface effect. The dark resistivity of GaTe1−xSex for 0.5 ≤ x ≤ 1 (i.e., predominantly H phase) is greater than that of the other instance of majority M-phase GaTe1−xSex for 0 ≤ x ≤ 0.4, owing to the larger bandgaps. The predominantly H phase GaTe1−xSex (0.5 ≤ x ≤ 1) also shows a greater photoconductive response under visible-light illumination because of the greater contribution from surface states. The superior light-emission and photodetection capability of the GaTe1−xSex multilayers (0 ≤ x ≤ 1) means that they can be used for future optoelectronic devices.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Near-infrared to red-light emission and carrier dynamics in full series multilayer GaTe1−xSex (0≤x≤1) with structural evolution

Muhimmah

Peng

et al. 2023

npj 2D Mater Appl

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“…Thus, we assume that this PL peak may be attributed to the emission from the h-GaTe fraction in the underlying thin film. However, the band gap value of the h-GaTe phase is a controversial topic, which has been either experimentally or theoretically claimed to be in a wide range from 1.0 to 1.6 eV. − To verify this uncertainty, low-temperature PL of the sample grown at 525 °C on the GaN/sapphire template was measured. Excitingly, the 10K-PL spectrum of this sample (red curve in Figure b) exhibited the same emission lineshape located at 1.46 eV.…”

Section: Resultsmentioning

confidence: 99%

Molecular Beam Epitaxy of Two-Dimensional GaTe Nanostructures on GaAs(001) Substrates: Implication for Near-Infrared Photodetection

Huynh¹,

Diep²,

Le³

et al. 2021

ACS Appl. Nano Mater.

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Molecular beam epitaxy of two-dimensional (2D) GaTe nanostructures on GaAs(001) substrates has been reported in this study. A trade-off between growth temperature and growth time (thickness) is a prerequisite for governing the crystal morphology of 2D GaTe materials from 2D epitaxial thin films to pseudo-one-dimensional (1D)/2D nanostructures (including nanorods, nanotriangles, and nanodendrites). Importantly, through real-time azimuthal reflection high-energy electron diffraction, a coexistence of hexagonal-GaTe (h-GaTe) and monoclinic-GaTe (m-GaTe) phases in the film was explored, corresponding to formation of lateral h/m-GaTe heterophase homojunctions. In addition, we found that utilizing a GaN/sapphire platform instead of the GaAs(001) substrate promotes formation of a single-phase h-GaTe in the thin film, which could be due to the surface-symmetry matching between the GaN/sapphire platform and the h-GaTe phase. Together with observing an asymmetric emission broad band of ∼1.76 eV that comes from the pseudo-1D m-GaTe phase, we provide convincing evidence that the emission feature located at 1.46 eV originates from the near-band-edge emission of the 2D h-GaTe epitaxial thin film. These results are meaningful in providing practical schemes to control the crystal phases of 2D GaTe materials and realize either hexagonal–monoclinic heterophase lateral homojunctions or single-phase h-GaTe epitaxial thin films on a wafer scale for future functional (opto)electronic devices, especially for near-infrared photodetectors.

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“…As is well known, the GaTe crystal generally exists in a stable monoclinic phase with space group C 2 2 P2 1 and the GaSe crystal has a stable hexagonal structure with D 3 1 ( P 6̅ m 2) symmetry. , In this case, a phase transformation accompanied by phase separation would easily take place when GaTe and GaSe are alloyed into a ternary GaTe 1– x Se x solid solution. However, the critical composition region inducing the phase transformation in GaTe 1– x Se x has always been in debate in the past years. ,, Some works demonstrated that the monoclinic–hexagonal transformation easily occurred in a wide Se concentration range of 0.35 ≤ x ≤ 0.7. , But, in fact, the smaller transition region of 0.27 ≤ x ≤ 0.35 was also reported in the obtained GaTe 1– x Se x alloys via the vapor growth method. , To the best of our knowledge, the phase transformation from GaTe-like to GaSe-like generally occurs in the middle region of x = 0.5 for the GaTe 1– x Se x alloys according to the law of thermodynamics.…”

Section: Introductionmentioning

confidence: 99%

Phase Transformation and Tunable Optoelectrical Properties of Two-Dimensional Layered GaTe_1–xSe_x Crystals

Gao

Zhang

et al. 2022

ACS Appl. Electron. Mater.

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The phase transformation threshold and mechanism of layered GaTe1–x Se x crystals have been controversial for a long time. Herein, we demonstrate that an extremely low Se content of 20% can induce the phase transformation of GaTe1–x Se x from monoclinic structure to hexagonal structure. Theoretical and experimental studies reveal that the introducing of Se dopants effectively stabilizes the host lattice of metastable h-GaTe and thus induces the transformation of GaTe1–x Se x from monoclinic to hexagonal lattice in the low Se doping range. The obtained GaTe1–x Se x crystals also display tunable band gaps from 1.65 to 1. 85 eV and near band edge emission from 755 to 675 nm with increasing Se content from x = 0 to x = 0.44. More importantly, in comparison with GaTe and GaSe, layered GaTe1–x Se x nanosheets exhibit p-type conductivity, higher carrier concentration, excellent photoresponse, and air stability. The fabricated GaTe1–x Se x nanosheet photodetectors also show outstanding performance in the UV and visible range including a high responsivity of 91.3 A/W, an excellent EQE of 3.16 × 104%, and a specific detectivity of 5.05 × 109 Jones.

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Dual phase two-color emission observed in van der Waals GaTe planes

Cited by 20 publications

References 53 publications

Near-infrared to red-light emission and carrier dynamics in full series multilayer GaTe1−xSex (0≤x≤1) with structural evolution

Near-infrared to red-light emission and carrier dynamics in full series multilayer GaTe1−xSex (0≤x≤1) with structural evolution

Molecular Beam Epitaxy of Two-Dimensional GaTe Nanostructures on GaAs(001) Substrates: Implication for Near-Infrared Photodetection

Phase Transformation and Tunable Optoelectrical Properties of Two-Dimensional Layered GaTe_1–xSe_x Crystals

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Dual phase two-color emission observed in van der Waals GaTe planes

Cited by 20 publications

References 53 publications

Near-infrared to red-light emission and carrier dynamics in full series multilayer GaTe1−xSex (0≤x≤1) with structural evolution

Near-infrared to red-light emission and carrier dynamics in full series multilayer GaTe1−xSex (0≤x≤1) with structural evolution

Molecular Beam Epitaxy of Two-Dimensional GaTe Nanostructures on GaAs(001) Substrates: Implication for Near-Infrared Photodetection

Phase Transformation and Tunable Optoelectrical Properties of Two-Dimensional Layered GaTe1–xSex Crystals

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Phase Transformation and Tunable Optoelectrical Properties of Two-Dimensional Layered GaTe_1–xSe_x Crystals