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

Abstract In this work, wafer-scale continuous and uniform MoS 2 /(HfO 2 ) x (Al 2 O 3 ) 1− x (HfAlO) heterojunctions were prepared by atomic layer deposition. The energy band alignment of MoS 2 /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 MoS 2 /Al 2 O 3 , MoS 2 /(HfO 2 ) 0.45 (Al 2 O 3 ) 0.55 , MoS 2 /(HfO 2 ) 0.60 (Al 2 O 3 ) 0.40 and MoS 2 /(HfO 2 ) 0.78 (Al 2 O 3 ) 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 MoS 2 /HfAlO interfaces exhibited type-I band alignment. Furthermore, a MoS 2 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 MoS 2 -based electronics and optoelectronics.