Band alignment of atomic layer deposited MoS2/(HfO2) x (Al2O3)1−x heterojunctions for device applications

Abstract

Abstract In this work, wafer-scale continuous and uniform MoS2/(HfO2) x (Al2O3)1−x (HfAlO) heterojunctions were prepared by atomic layer deposition. The energy band alignment of MoS2/HfAlO heterojunctions was systematically investigated using x-ray photoelectron spectroscopy. The valence band offsets were deduced to be 3.19 ± 0.1, 3.01 ± 0.1, 2.94 ± 0.1, and 2.91 ± 0.1 eV for the heterojunctions of MoS2/Al2O3, MoS2/(HfO2)0.45(Al2O3)0.55, MoS2/(HfO2)0.60(Al2O3)0.40 and MoS2/(HfO2)0.78(Al2O3)0.22, while the conduction band offsets were measured as 2.51 ± 0.1, 2.17 ± 0.1, 2.00 ± 0.1, and 1.85 ± 0.1 eV, respectively. All MoS2/HfAlO interfaces exhibited type-I band alignment. Furthermore, a MoS2 field-effect transistor with HfAlO as the gate dielectric layer was fabricated, and the gate leakage of the device was only a few picoamperes, which ensured high reliability and low power consumption. These encouraging results suggest that HfAlO is a promising dielectric material for applications in MoS2-based electronics and optoelectronics.