Stability of direct band gap under mechanical strains for monolayer MoS2, MoSe2, WS2 and WSe2

Abstract

Single layer transition-metal dichalcogenides materials (MoS 2 , MoSe 2 , WS 2 and WSe 2) are investigated using the first-principles method with the emphasis on their responses to mechanical strains. All these materials display the direct band gap under a certain range of strains from compressive to tensile (stable range). We have found that this stable range is different for these materials. Through studying on their mechanical properties again using the first-principles approach, it is unveiled that this stable strain range is determined by the Young's modulus. More analysis on strains induced electronic band gap properties have also been conducted.

Optical and Piezoelectric Properties of Strained Orthorhombic PdS2

“…These excellent properties have resulted in many applications, such as phototransistor [6,7], flexible optoelectronics [8], self-powered nanosystems [9,10] and smart MEMS/NEMS [8,11,12]. During the last decade, several TMDs have been extensively investigated, both in theory and experiment [2,[13][14][15][16][17].…”

“…Furthermore, some important properties distinguished from the traditional two-dimensional (2D) TMDs have been reported , such as excellent linear electronic and optical tunability [2]. Many previous studies have shown that one can tune the electronic and optical properties of the TMDs by applying mechanical strains [2,16,17,[20][21][22]. Although the optical properties of the monolayer PdS2, electron transport properties and stability of the bilayer and bulk PdS2 have been studied in references [2,23,24], there are very few studies on the first principles analysis of the orthorhombic PdS2.…”

“…In this work, we analysis the optical and piezoelectric properties of the orthorhombic PdS2 under symmetrical biaxial tensile deformation ranging between 0 and 8% using the ab initio simulation and modern theory of polarization. These methods has been used in many previous studies on the TMDs and piezotronics [2,16,17,22,[25][26][27]. Our aim is to theoretically explore the development of optical and piezoelectric properties for the orthorhombic PdS2 under different tensile strains.…”

Monolayer MoSe₂-Based Tunneling Field Effect Transistor for Ultrasensitive Strain Sensing

“…Among these, MoS2 is not suitable for tunnel FET applications due to its large band gap of 1.8 eV, which significantly reduces the band-to-band tunneling probability. Semiconducting MoTe2 (2H-phase) suffers from the stability issue [15], [20]. Therefore, this is not feasible for reliable FET realization, especially under external strain.…”

Photoluminescence of PdS2 and PdSe2 quantum dots

“…1 Recently, traditional transitionmetal dichalcogenide (TMD) semiconductors have become very promising candidates among the 2D materials series owing to the direct band gap behavior in monolayer TMDs at the K point, 2 along with excellent electronic, catalytic, optical, and mechanical properties. [3][4][5][6][7][8][9][10][11][12] Furthermore, TMD materials exhibit superior photoluminescence behavior, 3,4 piezoelectric properties, 13,14 and controllable optical performance by modulating valleys in the k space. [15][16][17][18] The development of several optoelectronic devices, such as strain sensors, 19 transistors, 20 and highly sensitive and broadband photodetectors [21][22][23] will highly benet from the assistance of these inherent properties.…”