Strong bulk-surface interaction dominated in-plane anisotropy of electronic structure in GaTe

Abstract

Recently, intriguing physical properties have been unraveled in anisotropic layered semiconductors, in which the in-plane electronic band structure anisotropy often originates from the low crystallographic symmetry and thus a thickness-independent character emerges. Here, we apply high-resolution angle-resolved photoemission spectroscopy to directly image the in-plane anisotropic energy bands in monoclinic gallium telluride (GaTe). Our first-principles calculations reveal the in-plane anisotropic energy band structure of GaTe measured experimentally is dominated by a strong bulk-surface interaction rather than geometric factors, surface effect and quantum confinement effect. Furthermore, accompanied by the thickness of GaTe increasing from mono- to few-layers, the strong interlayer coupling of GaTe induces direct-indirect-direct band gap transition and the in-plane anisotropy of hole effective mass is reversed. Our results shed light on the physical origins of in-plane anisotropy of electronic structure in GaTe, providing guidance to further improving the performance of electronic and optoelectronic devices based on the layered anisotropic semiconductors.

Allotropic Ga2Se3/GaSe nanostructures grown by van der Waals epitaxy: narrow exciton lines and single-photon emission

“…T. Okamoto et al have shown that low T S = 500 °C and VI/III ∼ 30 can apparently promote the formation of a vacancyordered Ga 2 Se 3 phase inclusions in the growing film. 20,40 In this regard, one can see that the conditions established for the MBE growth of Ga 2 Se 3 layers do not differ much from the conditions for GaSe, and the high VI/III flux ratio used for the growth of GaSe films with a Se valve cracking cell can promote the formation of Ga 2 Se 3 phase. In other words, the exact growth parameters of GaSe or Ga 2 Se 3 layers depend strongly on the setup used and require test growth processes.…”

“…T. Okamoto et al have shown that low T S = 500 °C and VI/III ∼ 30 can apparently promote the formation of a vacancy-ordered Ga 2 Se 3 phase inclusions in the growing film. 20,40…”

“…17,18 Unlike transition metal dichalcogenides, bulk GaSe has practically degenerate indirect and direct band gaps, which greatly simplifies the task of forming efficiently emitting structures. 19,20 Published low-temperature photoluminescence (PL) spectra of bulk GaSe are inhomogeneous and contain a number of lines that were attributed to free excitons and excitons bound at various defects 21 and various polytypes that differ from each other in the sequence of stacking in the unit cell. 22,23 When the number of monolayers is reduced to approximately six, GaSe emission disappears due to the very weak absorption of exciting light in indirect band gap structures.…”

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

“…Layered GaS, GaSe and GaTe materials all exhibit large out-of-plane anisotropy in their mechanical, optical, and electrical properties, a common feature in vdW compounds. ,− ,,− Uniquely, α-GaTe also displays in-plane anisotropy, which has traditionally been attributed to its asymmetric crystal structure. However, recently Lai et al claimed that strong bulk-surface interactions are the true underlying cause. Hexagonal GaSe crystals have garnered particular attention due to their nonlinear optical properties in the infrared (IR) range and their exceptional transparency between 650–18000 nm. , …”

Морфология поверхности и структурные свойства кристаллов GaTe после ионно-плазменной обработки

“…За счет своих уникальных свойств материал широко используется при разработке электронных приборов и устройств оптоэлектроники. Теллурид галлия относится к слоистым полупроводникам [1], легко формируется в виде 2D структур [2][3][4][5][6], имеет энергетическую диаграмму с прямой зоной [7][8][9], может существовать в различных структурных модификациях [10][11][12][13], имеет ярко выраженную анизотропию свойств [8,[14][15][16]. Эти и другие свойства позволяют применять кристаллы, пленки и 2D структуры (nanosheets, nanoflakes) GaTe при разработке фотодетекторов и солнечных элементов [17][18], транзисторов и фототранзисторов [19][20][21], элементов электроники и фотоники [22][23][24], устройств фотокатализа [25,26], литий-ионных элементов [27] и т. д. В настоящее время наряду с активным изучением низкоразмерных 2D систем проводятся комплексные исследования по формированию и использованию 1D объектов на основе теллурида галлия.…”