Graphene’s novel electrical, optical, and mechanical properties are affected both by substrate interaction and processing steps required to fabricate contacts and devices. Annealing is used to clean graphene devices, but this can lead to doping and defect changes and strain effects. There is often disagreement about which of these effects are occurring and which result in observed changes in Raman spectra. The effects of vacuum annealing on mechanically exfoliated pristine, suspended, and attached thin and thick few-layer graphene on SiO₂/Si are investigated here using scanning electron microscopy (SEM), Raman spectroscopy, and atomic force microscopy (AFM). Before annealing, Raman shows that the differences in 2D and G band positions and the appearance of a disorder-induced D band of all regions were mainly because of compressive or tensile structural deformations emerging through mechanical exfoliation instead of charge doping. Annealing at low temperature is sufficient to eliminate most of the defects. However, compressive strain is induced in the sheet by annealing at high temperature, and for thin regions increased substrate conformation leads to the apparent disappearance of the sheets. The intensity ratio of the 2D and G bands also reduces with induced compressive strain, and thus should not be used to detect doping.

This study investigates the effects of post-annealing on the properties of thermally evaporated antimony selenide (Sb₂Se₃) thin films. The prepared samples were annealed at different temperatures of 150, 200, 250 and 300 °C for half an hour. Different analytical techniques were used to investigate the properties of the annealed samples. XRD analysis confirmed the formation of orthorhombic Sb₂Se₃ in all samples, while variations in diffraction peak intensity and preferred orientation revealed a strong dependence of crystallographic texture on annealing temperature. EDX results indicated progressive selenium loss with increasing annealing temperature, particularly for the film annealed at 300 °C. AFM analysis showed that the 300 °C sample exhibited increased surface roughness compared with the films annealed at lower temperatures. All films demonstrated good optical absorption in the visible region with optical band-gap values ranging from approximately 1.0 to 1.3 eV, making them suitable for photovoltaic applications. Hall-effect measurements revealed significant changes in carrier concentration, mobility, and resistivity as a function of annealing temperature. Among the investigated conditions, the film annealed at 250 °C exhibited the most favorable combination of structural quality and electrical performance, indicating that this temperature provides an optimal annealing condition for thermally evaporated Sb₂Se₃ thin films considered for optoelectronic and photovoltaic applications.