High-performance semiconducting films with precisely engineered thicknesses and compositions are essential for developing next generation electronic devices, which are becoming more integrated, complex, and multifunctional. My talk will introduce the novel processes that enable atomic-scale control of the thickness and spatial composition of semiconducting films on the wafer-scale. These processes include: (i) the wafer-scale generation of monolayer van der Waals semiconductors such as transition metal dichalcogenides (TMDCs) via metal-organic chemical vapor deposition (MOCVD), (ii) the atomic-level engineering of vertical thickness and composition through the layer-by-layer assembly of TMDC monolayers, and (iii) the transfer of atomically engineered films, using their van der Waals nature, onto arbitrary substrates. These capabilities provide a new material platform for both fundamental research and practical applications, including incorporation into existing integrated circuit technology to form hybrid materials (i.e. TMDC/CMOS) and boost electrical and optical functionality.