Lattice vibrations and electronic properties of GaSe nanosheets from first principles

Bejani, Mousa; Pulci, Olivia; Barvestani, Jamal; Vala, A. Soltani; Bechstedt, F.; Cannuccia, Elena

doi:10.1103/physrevmaterials.3.124003

Cited by 6 publications

(5 citation statements)

References 47 publications

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“…Raman spectra of GaSe flakes with different NLs are recorded under a 532 nm excitation. In the range of 100–400 cm –1 , three prominent Raman modes, A 1 1 mode (∼132 cm –1 ), E 1 ′ (TO mode, 210 cm –1 ) mode, and A 1 4 mode (305 cm –1 ), are observed, which are attributed to the in-plane and out-of-plane vibrations of gallium and selenide atoms, respectively. − As seen in Figure b, the intensities of Raman modes in GaSe flakes exhibit a strong NL dependence, whose intensities rise to a peak at NL = 19 and then show a prominent second oscillatory peak at NL = 108. This NL dependence in Raman intensity is originated from the interference effect in a multilayer system as described in our previous studies. , The schematic images of atomic displacements of those modes are given in Figure c.…”

Section: Results and Discussionmentioning

confidence: 91%

Photo-oxidation Dynamics in GaSe Flakes Probed through Temporal Evolution of Raman Spectroscopy

et al. 2021

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The effect of native defect density on structure evolution during oxidation has not been systematically studied for two-dimensional (2D) materials. Photo-oxidation provides a way to fasten oxidation in 2D materials. The oxidation dynamics in atomically layered GaSe is systemically studied here through the temporal evolution of Raman spectroscopy. Two stages of oxidation processes are observed under above-gap laser irradiation in ambient conditions. First, the Raman intensity in GaSe flakes linearly decreases with the square root of oxidation time, and the slope shows a linear dependence on the square root of laser power. This stage is associated with photo-oxidation-induced structural damage with the formation of randomly distributed oxidation products, i.e., Ga2Se3, Ga2O3, and crystalline and amorphous selenium. A model is proposed to interpret the oxidation kinetics in GaSe flakes in terms of illumination time, laser power, and native defect density. Second, continuous change in slope is observed, which is due to the oxidative products merging to form a large oxidation lump. The evolution of defect density in GaSe flakes in terms of laser power, oxidation time, and native defect density during oxidation shines new light on the understanding of the stabilities of 2D materials in ambient environments.

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Section: Results and Discussionmentioning

confidence: 91%

Photo-oxidation Dynamics in GaSe Flakes Probed through Temporal Evolution of Raman Spectroscopy

et al. 2021

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“…The Raman peaks are consistent with the data reported in the literature. [39][40][41] The A 1g peaks with the highest intensity are the result of vibrations occurring out-of-plane, whereas the remaining peaks are the result of vibrations occurring in the crystal plane. Figure 1d presents a schematic cross-sectional view of a back gated GaSe FET with its electrical connections.…”

Section: Resultsmentioning

confidence: 99%

n‐Type GaSe Thin Flake for Field Effect Transistor, Photodetector, and Optoelectronic Memory

Kumar,

Pelella,

Intonti

et al. 2024

Adv Elect Materials

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The family of 2D chalcogenide semiconductors has been growing rapidly. Metal monochalcogenides, for instance, can enable new possibilities in functional electronics and optoelectronics. A Gallium Selenide (GaSe) thin flake is used to fabricate a back gated field effect transistor (FET) with n‐type conduction behavior and wide hysteresis at the ambient conditions. The device shows high mobility up to 28 cm2 V−1 s−1 with Ion/Ioff ratio over 103. Under the laser exposure, the device shows a decrease in the threshold voltage and a left‐shift of the transfer characteristic with a slight increase in the current. The transfer characteristic exhibits a hysteretic behavior with hysteresis width linearly dependent on the applied gate voltage. Moreover, the GaSe‐based FET shows a photo response with a photoresponsivity of 475 mAW−1 and detectivity of 4.6 × 1012 Jones. The photocurrent rise and decay times are 0.1 and 1.3 s, respectively. Furthermore, the GaSe FET device can be used as a performant memory device with well separated states and memory window enhanced by the laser exposure, confirming an optoelectronic memory class.

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“…Two-dimensional (2D) layered materials such as post-transition metal chalcogenides (PTMCs) M III − X (M III = In, Al, Ga and X = Se, Te, S) semiconductors are promising for electronic applications due to intriguing optical and vibrational properties [1][2][3][4] , including bandgap tunability from the IR to the UV spectral range and direct to indirect gap crossover as the number of layers decreases 5,6 , inverted sombrero like valence band dispersion for few layers 7,8 , and strong excitonic absorption 9,10 . Among these, GaTe exhibits two crystalline phases: a thermodynamically stable monoclinic (m-GaTe) 11 and a metastable hexagonal (h-GaTe) 12 , as shown by the bilayer (BL) stacking of Fig.…”

Section: Introductionmentioning

confidence: 99%

Two-dimensional single crystal monoclinic gallium telluride on silicon substrate via transformation of epitaxial hexagonal phase

et al. 2023

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Van der Waals (vdW) epitaxial growth of large-area and stable two-dimensional (2D) materials of high structural quality on crystalline substrates is crucial for the development of novel device technologies. 2D gallium monochalcogenides with low in-plane symmetry stand out among the layered semiconductor materials family for next-generation optoelectronic and energy conversion applications. Here, we demonstrate the formation of large-area, single crystal and optically active 2D monoclinic gallium telluride (m-GaTe) on silicon substrate via rapid thermal annealing induced phase transformation of vdW epitaxial metastable hexagonal gallium telluride (h-GaTe). Stabilization of multilayer h-GaTe on Si occurs due to the role of the first layer symmetry together with efficient GaTe surface passivation. Moreover, we show that the phase transformation of h-GaTe to m-GaTe is accompanied by the strain relaxation between Si substrate and GaTe. This work opens the way to the fabrication of single-crystal 2D anisotropic semiconductors on standard crystalline wafers that are difficult to be obtained by epitaxial methods.

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Lattice vibrations and electronic properties of GaSe nanosheets from first principles

Cited by 6 publications

References 47 publications

Photo-oxidation Dynamics in GaSe Flakes Probed through Temporal Evolution of Raman Spectroscopy

Photo-oxidation Dynamics in GaSe Flakes Probed through Temporal Evolution of Raman Spectroscopy

n‐Type GaSe Thin Flake for Field Effect Transistor, Photodetector, and Optoelectronic Memory

Two-dimensional single crystal monoclinic gallium telluride on silicon substrate via transformation of epitaxial hexagonal phase

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