Two-dimensional materials have gathered a great interest in recent years because of their unique chemical and physical properties, such as sizable bandgaps and indirect to direct bandgap transitions when monolayers are isolated. They appear with lamellar structures from which single monolayers can be extracted with exfoliation. There are different types of compounds including those belonging to the semiconductor family, in this communication will be considered GaS (Gallium Sulphide). GaS crystals were prepared using two different methods: CVT (Chemical Vapour Transport) in closed tube and PVT (Physical Vapour Transport) in open tube on silicon substrate [1]. The crystals obtained with the two methods, despite being of very different dimensions (cm and micro), they appear with lamellar structures from which single monolayers can be extracted with exfoliation. The crystals grown by CVT appear with yellow color with different sizes and as overlapping layers while the morphology of crystals grown on silicon by PVT was observed by Scanning Electron Microscopy (SEM) show low sizes with different morphologies (nanowires, nanobelts and plates). The composition of the crystals has been confirmed by EDX analysis. The structural properties have been studied by X-ray powder diffraction using a Siemens D6000 diffractometer which makes use of Ni-filtered CuK? radiation in scanning mode from 10 to 90° 2? with a step size of 0.05° and counting time of 10 s. For both crystals diffraction pattern shows the characteristic indexed peaks confirming the hexagonal structure of crystals. Ambient temperature Cathodoluminescence was used to study the emission. The spectra revealed in both samples the indirect bandgap related emission (near band edge - NBE) around 500 nm, which correspond to 2.48 eV and other peaks are related to defects luminescencein the lower energy region. The higher intensity of the defects related peaks in the nanostructured sample suggests a higher defect density. References [1].C.Paorici, G. AttoliniVapour growth of bulk crystals by PVT and CVT. Progress in crystal growth and Characterization of Materials 2004,48/49, 2. [2].O.A. BalitskiiV.P. Savchyn, P.V. SavchynThermal oxidation of indium and gallium sulphides.Physica B 2005, 355, 365.
Vapour phase growth and characterization of GaS
Giovanni Attolini;Marco Negri
2018
Abstract
Two-dimensional materials have gathered a great interest in recent years because of their unique chemical and physical properties, such as sizable bandgaps and indirect to direct bandgap transitions when monolayers are isolated. They appear with lamellar structures from which single monolayers can be extracted with exfoliation. There are different types of compounds including those belonging to the semiconductor family, in this communication will be considered GaS (Gallium Sulphide). GaS crystals were prepared using two different methods: CVT (Chemical Vapour Transport) in closed tube and PVT (Physical Vapour Transport) in open tube on silicon substrate [1]. The crystals obtained with the two methods, despite being of very different dimensions (cm and micro), they appear with lamellar structures from which single monolayers can be extracted with exfoliation. The crystals grown by CVT appear with yellow color with different sizes and as overlapping layers while the morphology of crystals grown on silicon by PVT was observed by Scanning Electron Microscopy (SEM) show low sizes with different morphologies (nanowires, nanobelts and plates). The composition of the crystals has been confirmed by EDX analysis. The structural properties have been studied by X-ray powder diffraction using a Siemens D6000 diffractometer which makes use of Ni-filtered CuK? radiation in scanning mode from 10 to 90° 2? with a step size of 0.05° and counting time of 10 s. For both crystals diffraction pattern shows the characteristic indexed peaks confirming the hexagonal structure of crystals. Ambient temperature Cathodoluminescence was used to study the emission. The spectra revealed in both samples the indirect bandgap related emission (near band edge - NBE) around 500 nm, which correspond to 2.48 eV and other peaks are related to defects luminescencein the lower energy region. The higher intensity of the defects related peaks in the nanostructured sample suggests a higher defect density. References [1].C.Paorici, G. AttoliniVapour growth of bulk crystals by PVT and CVT. Progress in crystal growth and Characterization of Materials 2004,48/49, 2. [2].O.A. BalitskiiV.P. Savchyn, P.V. SavchynThermal oxidation of indium and gallium sulphides.Physica B 2005, 355, 365.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
