Improvement of the stability and optoelectronic characteristics of molybdenum disulfide thin-film transistors by applying a nitrocellulose passivation layer

Nitrocellulose is proposed as a passivation layer for multilayer molybdenum disulfide (MoS₂) thin-film transistors (TFTs) to improve the stability of the devices. After the devised passivation layer was stacked, the threshold voltage shift of the nitrocellulose-passivated MoS₂ TFT after the positive-bias temperature stress tests decreased from 11.43 to 4.80 V. This enhanced stability was the result of the protection of the MoS₂ channel from external reactive molecules like H₂O, O₂, and others in the atmosphere. Not only the stability was improved; the electrical performance was also enhanced. The field effect mobility and on/off ratio increased 1.13 and 3.05 times, respectively, due to the narrowed width of the Schottky barrier from the interfacial dipoles between the nitrocellulose and the MoS₂ layers. Additionally, the formation of Mo-N bonding generated deep-level subgap states into the bandgap, which led to a higher probability of photoexcitation. Therefore, the MoS₂ TFT with a nitrocellulose passivation layer exhibited 202.35 A/W enhanced photoresponsivity, 1.83 × 10³ photosensitivity, and 9.94 × 10⁹ Jones detectivity under 635 nm light at 10 mW/mm².