arXiv subjects

Md Akibul Islam

Publications and source records attributed to Md Akibul Islam.

4 recordsLinked to original sources

arXiv2025

Multifunctional Oxide Nanosheets: Frictional, Hall, and Piezoelectric Deformation of 2D Ga2O3

Atomically thin oxides are increasingly recognized as an emerging class of 2D materials, yet their multifunctional properties have been far less investigated compared to other layered materials. Among these, gallium oxide is distinguished by its ultrawide bandgap, thermal stability, and mechanical rigidity, positioning it as a candidate material for nanoelectromechanical systems. In this study, the tribological, transport, and electromechanical properties of beta-Ga2O3 nanosheets were probed using atomic force microscopy (AFM)--based techniques. Friction force microscopy (FFM) was used to investigate interfacial sliding, and a dependence of friction on external bias was observed, which was attributed to defect-mediated charge trapping. Van der Pauw Hall measurements were conducted up to 400 $^{\circ}$C, through which the ultrawide bandgap nature of beta-Ga2O3 was confirmed, as electronic transport remained suppressed despite high thermal activation. Piezoresponse force microscopy (PFM) was further applied, and a measurable converse electromechanical response on the order of a few pm/V was revealed, consistent with oxygen-vacancy--induced symmetry breaking. By integrating tribological, electrical, and electromechanical measurements, it was demonstrated that beta-Ga2O3 nanosheets present a unique platform in which insulating stability, bias-tunable interfacial mechanics, and defect-enabled electromechanical activity coexist, offering new opportunities for multifunctional oxide nanodevices.

cond-mat.mtrl-sci↗

arXiv2025

High-magnitude, spatially programmable, and sustained strain engineering of 2D semiconductors

Crystalline two-dimensional (2D) semiconductors often combine high elasticity and in-plane strength, making them ideal for strain-induced tuning of electronic characteristics, akin to strategies used in silicon electronics. However, existing techniques have not achieved strain in 2D materials that is simultaneously high in magnitude (>1%), stable over long periods, and spatially programmable, meaning the strain level can be deterministically engineered across different regions of a single 2D layer. Here, we apply spatially programmable biaxial strain (e_b) up to 2.2% with spatial resolution of 0.13 %e_b um-1 in monolayer MoS2 via conformal transfer onto patterned substrates fabricated using two-photon lithography. The induced strain is stable for months and enables local band gap tuning of ~0.4 eV in monolayer MoS2, ~25% of its intrinsic band gap. We further extend the approach to bilayer WS2-MoS2 heterostructures. This strain-engineering technique introduces a new regime of strain-enabled control in 2D semiconductors to support the development of wide-spectrum optoelectronic devices and nanoelectronics with engineered electronic landscapes.

cond-mat.mtrl-sci↗

arXiv2024

Temperature Dependent Failure of Atomically Thin MoTe2

In this study, we systematically investigated the mechanical responses of monolayer molybdenum ditelluride (MoTe2) using molecular dynamics (MD) simulations. The tensile behavior of trigonal prismatic phase (2H phase) MoTe2 under uniaxial strain was simulated in the armchair and zigzag directions. We also investigated the crack formation and propagation in both armchair and zigzag directions at 10K and 300K to understand the fracture behavior of monolayer MoTe2 at different temperatures. The MD simulations show clean cleavage for the armchair direction, and the cracks were numerous and scattered in the case of the zigzag direction. Finally, we investigated the effect of temperature on Young's modulus and fracture stress of monolayer MoTe2. The results show that at a strain rate of 10^-4 ps^-1, the fracture strength of monolayer MoTe2 in the armchair and zigzag directions at 10K is 16.33 GPa (11.43 N/m) and 13.71 GPa (9.46 N/m) under a 24% and 18% fracture strain, respectively. The fracture strength of monolayer MoTe2 in the armchair and zigzag direction at 600K is 10.81 GPa (7.56 N/m) and 10.13 GPa (7.09 N/m) under a 12.5% and 12.47% fracture strain, respectively.

cond-mat.mtrl-sci↗

arXiv2023

Effect of Triangular Pre-Cracks on the Mechanical Behavior of 2D MoTe$_2$: A Molecular Dynamics Study

Among two-dimensional (2D) materials, transition metal dichalcogenides (TMDs) stand out for their remarkable electronic, optical, and chemical properties. In addition to being variable bandgap semiconductor materials, the atomic thinness provides flexibility to TMDs. Therefore, understanding the physical properties of TMDs for applications in flexible and wearable devices is crucial. Despite the growing enthusiasm surrounding two-dimensional transition metal dichalcogenides (TMDs), our understanding of the mechanical characteristics of molybdenum ditelluride (MoTe$_2$) remains limited. The mechanical properties of MoTe$_2$ deteriorate in the presence of pre-existing cracks or vacancy defects, which are very common in grown TMDs. In this study, the fracture properties and crack propagation of monolayer molybdenum ditelluride (MoTe$_2$) sheets containing pre-existing triangular cracks with various vertex angles are investigated by performing molecular dynamics (MD) simulations of uniaxial and biaxial tensile loading. Due to pre-crack length, angle, and perimeter variations, monolayer MoTe$_2$ with pre-existing cracks underwent considerable changes in Young's modulus, tensile strength, fracture toughness, and fracture strain values. We have found that the pre-cracked MoTe$_2$ is more brittle than its pristine counterpart. Regulated alteration of pre-crack angle under constant simulation conditions improved the uniaxial mechanical properties. Similarly, regulated alteration of the perimeter of the pre-crack resulted in improved biaxial mechanical properties. This study contributes to the foundational knowledge for advanced design strategies involving strain engineering in MoTe$_2$ and other similar transition metal dichalcogenides.

cond-mat.mtrl-sci↗