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

Abstract

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.

Growth Temperature Effects in Nanoscale-Thick GaTe Films on c-Sapphire Substrate by Molecular Beam Epitaxy: Implications for High-Performance Optoelectronic Devices

“…The Raman frequencies observed at approximately 114, 127, 142, and 196 cm −1 were identified as the A g modes, while those at 175 and 291 cm −1 were attributed to E 2g 1 and A 1g 2 , respectively. 32,47 The Raman peaks at 127 and 142 cm −1 , characteristic of h-GaTe, are distinctly observable. 32 Simultaneously, Raman peaks at 115, 175, 196, and 291 cm −1 , corresponding to m-GaTe, are clearly evident as depicted in Figure 4a.…”

“…Furthermore, we harnessed growth-temperature-dependent Raman scattering to delve into the structural behavior of GaTe, as elegantly displayed in Figure a. The Raman frequencies observed at approximately 114, 127, 142, and 196 cm –1 were identified as the A g modes, while those at 175 and 291 cm –1 were attributed to E 2g 1 and A 1g 2 , respectively. , The Raman peaks at 127 and 142 cm –1 , characteristic of h-GaTe, are distinctly observable . Simultaneously, Raman peaks at 115, 175, 196, and 291 cm –1 , corresponding to m-GaTe, are clearly evident as depicted in Figure a. − These peaks consistently exhibited intensity variations with changes in the growth temperature.…”

Broadband Photodetection of Centimeter-Scale T-Phase Gallium Telluride Grown by Molecular Beam Epitaxy

“…Currently, 2D GaTe has two crystal structures: m-GaTe and h-GaTe, as shown in Figure a,b, respectively. The layer configuration of GaTe consists of a quadruple layer containing four atomic layers of Te–Ga–Ga–Te. , For h-GaTe, the Ga–Ga bonds are completely perpendicular to the layer plane with an atomic stacking sequence of ABBA, forming a hexagonal crystal structure . On the other hand, m-GaTe presents a twisted posture, with one-third of the Ga–Ga bond in the structure changing from an out-of-plane position to an in-plane position .…”

Review of Nanolayered Post-transition Metal Monochalcogenides: Synthesis, Properties, and Applications

“…Single-crystal α-GaTe films have been synthesized on Si(111) substrates through a two-step MBE growth method based on the phase transition of β-GaTe. Zallo et al initially grew metastable β-GaTe films at 375 °C and induced the phase transition by rapidly heating the films to 550 °C for 30 min. The resulting films have thickness ranging from 2 to 18 layers with no grain boundaries and strong photoluminescence signals.…”