Scaling Up the 2D Epitaxy from 2-Inch to 300 mm Sapphire Substrates

Molybdenum Disuflide (MoS₂) and Tungsten Diselenide (WSe₂) are respectively the most promising n-type and p-type two dimensional (2D) semiconductors considered for future transistor scaling. Much of the research is hence ongoing to produce single crystal 2D films on large area wafers. The most common approach is the 2D epitaxial growth on sapphire substrates which are commercially available up to 200 and 300 mm wafer size. Sapphire are however known to exhibit an inhomogeous surface if care is not taken on their miscut orientation but also their surface preparation [1, 2]. One can thus deduce that his inhomegenity becomes more important for the 200/300 mm sapphire wafers compared to the 2 inch ones.<br/>In this vein, we investigate here the MOCVD growth of MoS₂ and WSe₂ on both 2 inch and 200/300 mm sapphire substrates. We start by sheding the light on the challenges that are faced when 200/300 mm substartes are used and the difference with their 2 inch counterpart. We then focus on the impact of surface preparation and growth conditions on the quality of grown MoS₂ and WSe₂films. We explain how the growth learning on 2 inch allows to upscale the growth on 200/300 mm substrates and how 300 single crystal 2D film can be obtained.<br/><br/>[1] W. Mortelmans et al., Nanotechnology 30, 465601 (2019)<br/>[2] Y Shi et al., ACS nano 15, 9482-9494 (2021)