Intersubband transitions in transition metal dichalcogenides (TMDs)

Summary form only given. The discovery of intersubband transitions in III-V semiconductor heterostructures [I] had a huge impact on large parts of the condensed matter physics community and ultimately led to the development of quantum well infrared photodetectors [2] and quantum cascade lasers [3]. One of the main constraints, however, are the strict lattice matching conditions of the heterostructures - limiting the available materials to combine - and its expensive and complicated growth.Here, we present an innovative measurement technique that allows us to overcome these constraints We observe resonant absorption in the conduction band of MoS2 and valence band of WSe2 that we can attribute to intersubband transitions. By varying the doping of the TMD flakes we can compare the extracted values of the absorption to a simple model for an infinite square well potential and find a good quantitative agreement.