New Mechanisms Towards Enhanced IR photon Detection in Multifunctional 2D Semiconductors

The main objective of the proposed research program is to realize enhanced IR photon detection based on novel physical mechanisms in new multifunctional two-dimensional (2D) semiconductors. In conventional IR photon detectors, the detectivity is given by DÀv(a/Gth ), where a is the absorption coefficient and Gth the thermal generation rate.1, 2 While a may be optimized from photonic engineering, Gth is limited by the fundamental physics of charge carrier scattering and recombination. 2D semiconductors are emerging candidates for advanced IR photon detection, but the same fundamental barriers to reducing Gth in conventional three-dimensional (3D) semiconductors exist in 2D. Exploiting novel physical mechanisms resulting from the coupling of multiple functionalities in 2D semiconductors, the PIs aim to overcome these barriers to drastically decrease Gth and thus increase detectivity. The first objective will be to establish IR photon-to-electric conversion in paraelectric and ferroelectric 2D semiconductors where electron coupling to transverse optical (TO) phonons or static electric polarization gives rise to efficient screening of photocarriers, thus reducing recombination and Auger scattering responsible for Gth. The second objective will be to realize IR photon detection in 2D magnetic semiconductors where strong exciton-magnon coupling will be used for the transduction of IR photons to magnons, with orders-of-magnitude lower Gth than those of conventional electric detection. Both objectives will target the development of next-generation IR photon detectors, including room temperature devices.