For the first time, we report the positive bias temperature instability of the back gated multilayer MoS2 n-MOSFETs with Al2O3 gate dielectric. In the stress phase, the Id - Vg curve shifts to the positive gate bias. In the recovery phase, it shifts back to the negative gate bias. After 5000 s recovery, it completely recovers to that of the fresh device. The results indicate that the voltage shift is solely due to trapping and detrapping of the pre-existing border traps in the Al2O3 dielectric. The traps consist of fast and slow components with the capture time constants of 7 and 1.8 × 102 s and the emission time constants of 15 and 1.0 × 103 s, respectively. The results from first-order trapping and detrapping calculations are in overall agreements with 12 measured ΔVg curves including six under stress voltages and six in the recovery phases. The energy densities for the fast and slow traps are derived to be in the order of 1013 cm-2 eV-1 above the bottom of the MoS2 conduction band.
- oxide trap