Improved photoswitching response times of MoS₂ field-effect transistors by stacking p -type copper phthalocyanine layer

Photoswitching response times (rise and decay times) of a vertical organic and inorganic heterostructure with p-type copper phthalocyanine (CuPc) and n-type molybdenum disulfide (MoS₂) semiconductors are investigated. By stacking a CuPc layer on MoS₂ field effect transistors, better photodetection capability and fast photoswitching rise and decay phenomena are observed. Specifically, with a 2 nm-thick CuPc layer on the MoS₂ channel, the photoswitching decay time decreases from 3.57 s to 0.18 s. The p-type CuPc layer, as a passivation layer, prevents the absorption of oxygen on the surface of the MoS₂ channel layer, which results in a shortened photoswitching decay time because adsorbed oxygen destroys the balanced ratio of electrons and holes, leading to the interruption of recombination processes. The suggested heterostructure may deliver enhanced photodetection abilities and photoswitching characteristics for realizing ultra-thin and sensitive photodetectors.