International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

This work presents a combined experimental and simulation study of resist profile evolution in electron beam lithography (EBL) using poly(methyl methacrylate) (PMMA) resist. The influence of key process parameters, including exposure dose, electron beam energy, and resist thickness on the resist profile formation, sidewall shape, and feature fidelity is systematically investigated. Particular attention is given to proximity effects caused by forward and backscattered electrons, which lead to dose redistribution and profile distortions. Experimental results show a strong dependence of PMMA resist profiles on lithographic conditions, affecting sidewall angle and linewidth variation. Bilayer PMMA systems are also examined to evaluate improvements in profile control and undercut formation for lift-off processes. Simulation of resist development is employed to model resist profile evolution and predict structural changes under varying conditions. The comparison between experimental and simulated results demonstrates good agreement, confirming the validity
of the modeling approach. The study provides deeper insight into PMMA resist behavior and supports optimization of EBL process parameters for improved nanoscale patterning accuracy.

Two-dimensional (2D) materials such as graphene and tungsten disulfide (WS₂ ) are promising candidates for gas sensors due to their unique electrical and surface properties. Graphene exhibits high conductivity and mechanical strength, while its oxidized or functionalized forms enhance chemical reactivity and gas adsorption. WS₂ , a semiconducting transition metal dichalcogenide, shows strong surface interactions with gases, enabling sensitive detection even at room temperature.
In this work, graphene and WS₂ thin films were characterized to evaluate surface morphology, uniformity, and structural quality. Graphene films were prepared by chemical vapor deposition (CVD) and transferred onto SiO₂ /Si substrates, while WS₂ films with thicknesses of 20 nm and 50 nm were obtained via CVD and sputtering. Surface analysis using scanning electron microscopy (SEM) and 3D laser microscopy revealed that graphene films are highly uniform and smooth, whereas WS₂ films exhibit thickness-dependent surface roughness and texture. These findings provide insights into the relationship between film morphology and gas sensing performance, highlighting the potential of both materials for sensor applications.

In this paper, a two-dimensional (2D) material graphene with exceptional electronic and mechanical properties is discussed as a promising candidate for chemiresistive sensor applications. High surface area and superior charge carrier mobility of graphene enable rapid and sensitive detection of gaseous analytes, making it an attractive alternative to conventional metal oxide semiconductor (MOS) sensors. The review of recent advancements in graphene-based chemiresistive gas sensors is done, highlighting their operational principles, fabrication techniques, and performance enhancements through material modifications such as reduced graphene oxide (rGO). Additionally, we examine the application of graphene sensors in environmental monitoring, where their ability to detect pollutants like NO₂ , NH₃ , and CO₂ with high sensitivity and low power consumption provides a significant advantage over traditional sensing technologies. Despite these advancements, challenges such as selectivity, standardization, and sensor stability remain critical areas for future research.

This paper presents a study on the current state of research and use of dichalcogenides of transition metals, particularly WS2. The properties of WS2 in the context of its application in sensor technology and highlight the anticipated advantages of nanostructured disulfides are discussed.