Gamma irradiation effect studies on monolayer molybdenum disulfide on copper substrates

Molybdenum disulfide (MoS₂) is a two-dimensional material which has demonstrated semiconducting behavior [1]. Different kinds of irradiations create the defects in molybdenum disulfide (MoS₂) structure, different types of irradiations modulate the density of sulfur vacancies in MoS₂[1]. MoS₂ based and other 2-D materials-based devices and sensors are used in harsh environments [1]. In [2] authors have demonstrated studies of gamma irradiation on mono layer graphene. To develop and fabricate the MoS₂-based devices and sensors, nanoelectronics instrumentation such as Transmission Electron Spectroscopy (TEM), Scanning Electron Microscopy (SEM), Raman Spectroscopy, X-ray Photo-Electron Diffraction (XPS) techniques are required for characterization of MoS₂. Moreover, these radiation techniques, have huge impacts on electronic and optical properties of MoS₂ [3]. So, it is important to study irradiation effects on the crystal structure and properties of MoS₂. In this work, Co-60 source was used for the irradiation, which has nominal irradiation dose 2.07 Gy/min (207 rad/Min) (±5%). We have irradiated gamma-rays on four samples of single-layer molybdenum disulfide over copper substrate. We exposed the irradiation dose of 1.0 kGy (100 krad), 1.75 kGy (175 krad), 2.65 kGy (265 krad) and 3.0 kGy (300 krad) of irradiations on sample number one, two, three and four respectively. Through the Raman Spectroscopy, we studied E¹_2g, A_1g peaks. A_1g peak is at 403.6 cm^-1 and E¹_2g peak is at 384.7 cm^-1 in pristine MoS₂ Raman spectroscopy. Raman spectroscopy is nondestructive tool for characterization of S vacancies in MoS₂.