Tunable 2H–TaSe2 room-temperature terahertz photodetector

Two-dimensional transition metal dichalcogenides (TMDs) provide fertile ground to study the interplay between dimensionality and electronic properties because they exhibit a variety of electronic phases, such as semiconducting, superconducting, charge density waves (CDW) states, and other unconventional physical properties. Compared with other classical TMDs, such as Mott insulator 1T–TaS2 or superconducting 2H–NbSe2, bulk 2H–TaSe2 has been a canonical system and a touchstone for modeling the CDW measurement with a less complex phase diagram. In contrast to ordinary semiconductors that have only single-particle excitations, CDW can have collective excitation and carry current in a collective fashion. However, manipulating this collective condensation of these intriguing systems for device applications has not been explored. Here, the CDW-induced collective driven of non-equilibrium carriers in a field-effect transistor has been demonstrated for the sensitive photodetection at the highly-pursuit terahertz band. We show that the 2H–TaSe2-based photodetector exhibits a fast photoresponse, as short as , and a responsivity of over 27 V/W at room temperature. The fast response time, relative high responsivity and ease of fabrication of these devices yields a new prospect of exploring CDW condensate in TMDs with the aim of overcoming the existing limitations for a variety of practical applications at THz spectral range.