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.