Impact of the channel length on molybdenum disulfide field effect transistors with hafnia-based high- k dielectric gate

Yanxiao Sun , Gang Niu , Wei Ren , Jinyan Zhao , Yankun Wang , Heping Wu , Luyue Jiang , Liyan Dai , Ya-Hong Xie , Pedro Rojo Romeo (1) , Jordan Bouaziz , Bertrand Vilquin (2)

1 INL - I-Lum - INL - Ingénierie et conversion de lumière (i-Lum)
2 INL - MFN - INL - Matériaux Fonctionnels et Nanostructures

Field effect transistors (FETs) using two-dimensional molybdenum disulfide (MoS 2) as the channel material has been considered one of the most potential candidates for future complementary metal-oxide-semiconductor technology with low power consumption. However, the understanding of the correlation between the device performance and material properties, particularly for devices with scaling-down channel lengths, is still insufficient. We report in this paper back-gate FETs with chemical-vapor-deposition grown and transferred MoS 2 and Zr doped HfO 2 ((Hf,Zr)O 2 , HZO) high-k dielectric gates with channel lengths ranging from 10 to 30 μm with a step of 5 μm. It has been demonstrated that channels with the length to width ratio of 0.2 lead to the most superior performance of the FETs. The MoS 2 /HZO hybrid FETs show a stable threshold voltage of ∼1.5 V, current on/off ratio of >10 4 , and field effect mobility in excess of 0.38 cm 2 V −1 s −1. The impact of the channel lengths on FET performance is analyzed and discussed in depth. A hysteresis loop has been observed in the I ds − Vgs characteristics of the hybrid FETs, which has been further studied and attributed to the charge effect at the interfaces. The HZO films show a relatively weak ferroelectric orthorhombic phase and thus serve mainly as the high-k dielectric gate. Charge trapping in the HZO layer that might induce hysteresis has been discussed. Our results show that MoS 2 /HZO hybrid FETs possess great potential in future low power and high-speed integrated circuits, and future work will focus on further improvement of the transistor performances using ferroelectric HZO films and the study of devices with even shorter MoS 2 channels.

Domaines: Matériaux; Micro et nanotechnologies/Microélectronique; Science des matériaux [cond-mat.mtrl-sci]; Matériaux

Yanxiao Sun, Gang Niu, Wei Ren, Jinyan Zhao, Yankun Wang, et al.. Impact of the channel length on molybdenum disulfide field effect transistors with hafnia-based high- k dielectric gate. AIP Advances, 2021, 11 (6), pp.065229. ⟨10.1063/5.0055574⟩. ⟨hal-03269195⟩