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Mechanical stirring of bulk Te in N‐methyl‐2‐pyrrolidone (NMP) solution at room temperature resulted in the formation of free‐standing few‐layer (∼1.2–2.8 nm) crystalline ultrathin nanosheets of tellurene with a large lateral thickness (∼1–1.6 μm) as confirmed by atomic force microscopy (AFM). High‐resolution transmission electron microscopy (HRTEM) confirms the presence of α‐ and β‐phases of tellurene. First‐principle density functional theoretical (DFT) based electronic structure calculations demonstrate the indirect band gap of bi‐layer β‐tellurene. The band gap decreases with increasing number of layers in the tellurene nanosheet. [ABSTRACT FROM AUTHOR]

To develop wide bandgap materials for solar cells and other optoelectronic devices, undoped hydrogenated silicon oxide (SiOx:H) thin films are prepared by conventional radio frequency plasma enhanced chemical vapor deposition (RF PECVD) method. The variation of carbon dioxide dilution ( Y c ) on optoelectronic and structural properties are studied thoroughly by keeping silane and hydrogen gas flow fixed. Surface morphology of the SiOx:H films have been studied by Field Emission Scanning Electron Microscopy (FESEM) and Atomic Force Microscopy (AFM). Distinct silicon nanocrystallites of average diameter ∼ 3–6 nm embedded uniformly in amorphous SiOx network have been observed in high resolution Transmission Electron Microscopy (HRTEM). From Fourier Transform Infrared spectra (FTIR), it is observed that oxygen content ( C o ) increases initially with Y c and afterwards it decreases. Strong room temperature photoluminescence (PL) peak is obtained for the as-deposited films having lower oxygen content ( C o ). The origin of room temperature PL spectra and its correlation with C o can be explained by quantum confinement effect (QCE) theory. In the current study, undoped hydrogenated silicon oxide (SiOx:H) films were prepared by varying carbon dioxide dilutions with fixed silane and hydrogen gas flow, and a strong room temperature photoluminescence peak is observed for lower value of oxygen content. The microstructural properties of the films have also been studied by AFM, FESEM and HRTEM. In TEM study, a uniform distribution of silicon nanoparticles of average diameter ∼3–6 nm is clearly observed over the amorphous SiOx:H network. [ABSTRACT FROM AUTHOR]