Work

Spatio-chemical characterization and elimination of localized growth aberrations on monolayer MoS2 for enhanced performance top gated FETs with scaled ALD oxides

Year: 2025

Type: article

Abstract: • IR-PiFM maps identify growth artefacts on CVD grown monolayer MoS 2 as MoO x particles. • Sacrificial Al 2 O 3 layer cleaning process removes MoS 2 surface contaminants effectively. • Thin conformal ALD seed layer (∼1.3 nm) used for high-k gate oxide on monolayer MoS 2. • Cleaned MoS 2 FETs show 10–100 × higher on-current, lower SS and lower variability. • Process is CMOS-compatible and scalable for wafer-level applications. Obstacles towards the widespread use of two-dimensional materials, including MoS 2 , are high-quality large-scale growth of low defect density monolayers. A novel surface cleaning procedure, applicable in device technology, has been developed based on the use of an ALD sacrificial layer to eliminate growth aberrations. The imperfections on MoS 2 were identified using infrared photo-induced force microscopy (IR-PiFM) as MoO x particles deposited during CVD growth process. The utility of the procedure was tested through the fabrication of top gated field effect transistors (FETs) using a bilayer stack of low temperature ALD Al 2 O 3 (LT Al 2 O 3 ) seed layer followed by HfO 2 as the gate oxide. It was observed that the cleaning process results in 1–2 orders of magnitude improvement in the on-current, with a ∼30 % reduction in subthreshold swing, along with lower device variability.

Source: Applied Surface Science

DOI: 10.1016/j.apsusc.2025.164904