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

摘要

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.

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