An n-type MoS2 monolayer grown by chemical vapor deposition method was partially hybridized with an organic semiconducting p-type tetracene thin film. The photoluminescence (PL) intensity in the hybrid region of the MoS2/tetracene is clearly lower than that of pristine tetracene because of the charge-transfer effect, which was confirmed by the decrease in exciton lifetimes. Decrease in the temperature led to blue-shift in the PL peak position of MoS2 layers and, consequently, the PL intensities of both tetracene and MoS2 considerably increased owing to the decrease in phonon interaction. The PL spectra of bound excitons in the hybrid region were clearly observed at low temperatures, indicating the formation of trap states. The lateral-type n-p heterojunction field-effect transistors (FETs) using the MoS2/tetracene hybrid as an active layer showed gate-tunable rectification I-V and anti-ambipolar field-effect characteristics with hysteresis effect. The charge transport characteristics across the n-p heterojunction of the hybrid region of the FET can be explained in terms of the Shockley-Read-Hall trap-intermediated tunneling and Langevin recombination mechanisms. To improve the performance of MoS2/tetracene-based FET, a dielectric hexagonal boron nitride (h-BN) thin layer was inserted between the SiO2 surface and the active MoS2 layer. We observed the decrease in the hysteresis effect and threshold voltage of the h-BN/MoS2/tetracene-based FETs due to the decrease in the number of traps at the interface. The performance of h-BN/MoS2/tetracene FET device was also enhanced after the annealing process.
Bibliographical noteFunding Information:
This research was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (No. 2015R1A2A2A01003805 and 2018R1A2B2006369); Center for Advanced Meta-Materials (CAMM, as Global Frontier Project) (CAMM-2014M3A6B3063710). The authors thank Dr Weon-Sik Chae, KBSI Daegu Center, for the fluorescence lifetime measurements.
ASJC Scopus subject areas
- General Materials Science