Silicon Nitride Stress Liner Impacts On Mos2 Photodetectors

Strain engineering has been reported to improve the optical and electrical properties of two-dimensional materials, and the adjustable bandgap of MoS2 has great application value in strain engineering. In this work, to explore the influence of the Si3N4 stress liner on the MoS2 photodetector, plasma enhanced chemical vapor deposition was used to deposit a 5nm Si3N4 film on the surface of the device to introduce strain. The simulation results show that there is tensile strain in the MoS2 area under a Si3N4 layer, which can decrease the bandgap and electron effective mass of MoS2. The measurement results of the device show that the Si3N4 stress liner devices exhibit a higher light response than the Al2O3/MoS2/sapphire photodetector (control devices) under 365 and 460nm laser illuminations. The maximum photocurrent (I-ph) and responsivity (R) of the stress liner device under 365nm illumination are 4.1mA and 739.9A/W, respectively, which are more than 30 times the corresponding value of the control device. Also, the maximum specific detectivity (D*) reached 2.5x10(11)Jones, and the lowest noise equivalent power is 8.7x10(-16)W/Hz(1/2). Our work proved the feasibility of the Si3N4 stress liner to improve the performance of MoS2 photodetectors.