Modulating the carrier transport at 2D semiconductor/high-k oxide interfaces with 2D hBN interfacial layers

Abstract

The high-k oxide/semiconductor interface is a key component of two-dimensional (2D) field-effect transistors. However, the influence of interfacial properties, such as interfacial disorder, interfacial thermal dissipation, and remote phonon scattering on the carrier transport properties of 2D semiconductors, has not been well understood. Here, we modulate the high-k oxide/2D semiconductor interface with the 2D low-k insulator hBN and reveal the effects of high-k oxide/2D semiconductor interfacial properties on the intrinsic carrier transport of 2D semiconductors. Low-field transport measurements show that the field-effect mobility (μFE) of 2D devices with a MoS2/HfO2 interface deteriorates more severely with gate voltage than that of the devices with the MoS2/hBN/HfO2 interface, indicating that interfacial disorder scattering may affect the carrier transport in 2D devices. The gate voltage and temperature dependence of μFE in 2D devices with MoS2/HfO2 and MoS2/hBN/HfO2 interfaces suggests that remote phonon scattering may not play an important role in the 2D devices. High-field transport measurements show that the saturation velocity (νsat) of 2D devices with MoS2/hBN/HfO2 interfaces is much higher than that of devices with MoS2/HfO2 interfaces, which could be attributed to more efficient interfacial thermal dissipation. Notably, with a 3-layer hBN interfacial layer, the νsat of MoS2 is enhanced by ∼14%–21%, reaching ∼4.8 × 106 cm/s at room temperature. This is the highest value achieved without applying ultrafast pulsing measurements. By modulating the interfacial properties with 2D hBN, our study provides a clearer understanding of the influence of high-k oxide/2D semiconductor interface on the carrier transport of 2D semiconductors.