  The emergence of semiconducting materials with inert or dangling bond-free
surfaces has created opportunities to form van der Waals heterostructures
without the constraints of traditional epitaxial growth. For example, layered
two-dimensional (2D) semiconductors have been incorporated into heterostructure
devices with gate-tunable electronic and optical functionalities. However, 2D
materials present processing challenges that have prevented these
heterostructures from being produced with sufficient scalability and/or
homogeneity to enable their incorporation into large-area integrated circuits.
Here, we extend the concept of van der Waals heterojunctions to semiconducting
p-type single-walled carbon nanotube (s-SWCNT) and n-type amorphous indium
gallium zinc oxide (a-IGZO) thin films that can be solution-processed or
sputtered with high spatial uniformity at the wafer scale. The resulting
large-area, low-voltage p-n heterojunctions exhibit anti-ambipolar transfer
characteristics with high on/off ratios that are well-suited for electronic,
optoelectronic, and telecommunication technologies.
