Terahertz photonics

Abstract:

[This corrects the article DOI: 10.1021/acsenergylett.3c01368.].

Abstract:

Optical Pump Terahertz Probe (OPTP) spectroscopy is a well-established measurement technique with which charge-carrier dynamics of semiconductor nanowires (NW) can be extracted in a noncontact manner. Here in this work, we employ OPTP spectroscopy for measuring temperature-dependent photoconductivity spectra of 3D Dirac Cd 3 As 2 semi-metal nanowires, revealing a high Extrinsic carrier concentration of ∼2.0x1017cm−3 and ultrahigh carrier mobility of up to ∼13x103cm2V−1s−1 at a temperature of 5 K.

Abstract:

Topological insulator (TI) materials are emerging as novel materials for spintronic applications. Here, we demonstrate helicity-dependent THz emission from Dirac semi-metal Cd 3 As 2 nanowires and used scattering-type scanning optical microscopy (s-SNOM) to identify potential single nanowire candidates for device applications. The preliminary investigation data of a candidate nanowire shows a homogenous topography and constant dielectric function in the MIR range. Indicating high-quality crystalline growth ideal for topological characterization.

Abstract:

Topological materials have rapidly gained interest as contenders for development of coherent, controllable terahertz emitters. Possessing Weyl nodes either at the surface or within the bulk, they host spin-polarised, helicity-dependent currents that offer possibility to control the emitted THz pulse by changing the polarization of the optical pulses generating the radiation. Here, we show that upon near-infrared excitation at oblique incidence, multi-cycle pulses are generated with a narrow bandwidth of ∼0.4 THz for cadmium arsenide bulk crystals and nanowire ensembles. Both the bandwidth and peak emission frequency of the generated THz radiation can be tuned by respectively varying the photon helicity and angle of incidence of the photoexcitation light.

Abstract:

Metal halide perovskite semiconductors have shown significant potential for use in photovoltaic (PV) devices. While fabrication of perovskite thin films can be achieved through a variety of techniques, thermal vapor deposition is particularly promising, allowing for high-throughput fabrication. However, the ability to control the nucleation and growth of these materials, particularly at the charge-transport layer/perovskite interface, is critical to unlocking the full potential of vapor-deposited perovskite PV. In this study, we explore the use of a templating layer to control the growth of coevaporated perovskite films and find that such templating leads to highly oriented films with identical morphology, crystal structure, and optoelectronic properties independent of the underlying layers. Solar cells incorporating templated FA0.9Cs0.1PbI3–xClx show marked improvements with steady-state power conversion efficiency over 19.8%. Our findings provide a straightforward and reproducible method of controlling the charge-transport layer/coevaporated perovskite interface, further clearing the path toward large-scale fabrication of efficient PV devices.