Probing Electronic States in Monolayer Semiconductors through Static and Transient Third-Harmonic Spectroscopies

• Electronic states and their dynamics are of critical importance for electronic and optoelectronic applications. Here, various relevant electronic states in monolayer MoS2, such as multiple excitonic Rydberg states and free-particle energy bands are probed with a high relative contrast of up to ≥200 via broadband (from ≈1.79 to 3.10 eV) static third-harmonic spectroscopy (THS), which is further supported by theoretical calculations. Moreover, transient THS is introduced to demonstrate that third-harmonic generation can be all-optically modulated with a modulation depth exceeding ≈94% at ≈2.18 eV, providing direct evidence of dominant carrier relaxation processes associated with carrier–exciton and carrier–phonon interactions. The results indicate that static and transient THS are not only promising techniques for the characterization of monolayer semiconductors and their heterostructures, but also a potential platform for disruptive photonic and optoelectronic applications, including all-optical modulation and imaging. 

Subject headings

TEKNIK OCH TEKNOLOGIER  -- Materialteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering (hsv//eng)

NATURVETENSKAP  -- Fysik -- Atom- och molekylfysik och optik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Atom and Molecular Physics and Optics (hsv//eng)

Keyword

Electronic states

Harmonic analysis

Harmonic generation

Layered semiconductors

Modulation

Molybdenum compounds

Transition metals

Dichalcogenides

Electronics applications

Excitonics

Monolayer transition metal dichalcogenides

Optoelectronic applications

Static third-harmonic spectroscopy

Third harmonic

Third-harmonic generation

Transient third-harmonic spectroscopy

Monolayers

Publication and Content Type

ref (subject category)

art (subject category)