Photogating induced high sensitivity and speed from heterostructure of few-layer MoS₂ and reduced graphene...

Over the past few years, two-dimensional transition metal dichalcogenides (2D-TMDC) have attracted huge attention due to their high mobility, high absorbance, and high performance in generating excitons (electron and hole pairs). Especially, 2D molybdenum disulfide (MoS₂) has been extensively used in optoelectronic and photovoltaic applications. Due to the low photo-to-dark current ratio (I_photo/dark) and low speed, pristine MoS₂-based devices are unsuitable for these applications. So, they need some improvements, i.e., by adding layers or decorating with materials of complementary majority charges. In this work, we decorated pristine MoS₂ with reduced graphene oxide (rGO) and got improved dark current, I_photo/dark, and response time. When we compared the performance of pristine MoS₂ based device and rGO decorated MoS₂ based device, the rGO/MoS₂-based device showed an improved performance of responsivity of 3.36 A W^-1, along with an I_photo/dark of about 154. The heterojunction device exhibited a detectivity of 4.75 × 10¹² Jones, along with a very low response time of 0.184 ms. The stability is also outstanding having the same device performance even after six months.