We report pulsed terahertz (THz) emission from solution-processed metal halide perovskite films with electric field 1 order of magnitude lower than p-InAs, an efficient THz emitter. Such is enabled by a unique combination charge separation, high carrier mobilities, and more importantly surface defects. The mechanism generation was identified investigating the dependence amplitude on defect densities, excess carriers, excitation intensity energy, temperature, external field. also show for...

We demonstrate that the rectifying field effect transistor, biased to subthreshold regime, in a large signal regime exhibits super-linear response incident terahertz (THz) power. This phenomenon can be exploited variety of experiments which exploit nonlinear response, such as autocorrelation measurements, for direct assessment intrinsic time using pump-probe configuration or indirect calibration oscillating voltage amplitude, is delivered device. For these purposes, we employ broadband...

(GaIn)(AsBi) layers were grown on a GaAs substrate. Their alloy composition, structural characteristics as well the optical and electrical parameters determined. It was found that by incorporating Bi In into lattice of GaAs, energy bandgaps can be narrow 0.6 eV. These epitaxial quaternary bismide alloys have shorter than one picosecond carrier lifetime relatively large dark resistivity, demonstrating this material is good candidate for ultrafast optoelectronics applications. Thick used...

Terahertz (THz) pulse generation from p-InAs, p-InSb, and n-InSb epitaxial layers are investigated using 1.55-μm wavelength femtosecond laser pulses for photoexcitation. The samples of (111) crystallographic orientation resulting in anisotropic photoconductivity. Experiments have shown that THz InAs is mainly due to photocurrent the surface electric field while a dominant mechanism InSb optical rectification. At high excitation fluencies, more efficient than p-InAs. In presence an external...

Abstract Characterizing subcells in two-terminal multi-junction (M-J) solar cells is challenging due to the lack of direct electrical access. This work presents a novel contactless spectral characterization technique for analysing individual subcells. The involves probing terahertz (THz) radiation generated by femtosecond laser pulse excitation and varying exciting wavelength selectively absorb light desired subcell. registered THz integral then proportional induced photocurrent that...

Abstract Multilayer MoS 2 , MoSe and WSe crystals were excited with femtosecond optical pulses of various wavelengths. The emitted terahertz (THz) radiation found to be the most intense at photon energies coinciding direct energy gap K points Brillouin zone corresponding materials. It was shown that transition metal dichalcogenides different dopant type emit THz opposite polarity, suggesting surface field plays a role in emission. Nevertheless, pump–THz probe experiments contradicted...

Spectral dependences of the amplitudes terahertz (THz) transients radiated from a GaSe surface after its excitation by femtosecond optical pulses with photon energies in range 1.8 eV to 3.8 were used for study electron energy band structure this layered crystal. The separation 0.21 between main Γ valleys and satellite K conduction was determined maximum position THz spectrum; polarity became inverted at higher than 3 due onset transitions second, lower lying valence band.

Pulsed terahertz emission excitation spectra from germanium crystals are being presented. The most intense pulses emitted at quanta energies coinciding with technologically significant telecommunication wavelengths. generation mechanisms an interplay of the photocurrent surge in surface electric field and photo-Dember effect. Remarkably, is also observed below direct bandgap this material even when photoexcited a normal. This result broken symmetry effective electron mass L valleys.

Lattice-matched GaInAs p - i n diodes of different -region thicknesses have been MBE grown on -type InP (100) and (111) crystallographic orientation substrates. It has found that terahertz emission from such structures when illuminated with femtosecond laser pulses can be more efficient than the known to date best surface emitter -InAs. The explanation generation mechanism is based ultrafast photocurrent effects. Anisotropic transient photocurrents causing 3 ϕ azimuthal angle dependence are...

An undoped GaSb epitaxial layer has been grown on a GaAs substrate by molecular beam epitaxy. It found that could be potential surface terahertz (THz) emitter photoexcited 1.55 μm femtosecond laser pulses since the maximum optical-to-THz power conversion efficiency is at around this wavelength. The THz field strength 10 dB weaker as compared with generated from narrow-gap InAs these energies of quanta. Furthermore, samples were exposed to constant magnetic which enhances emission and allows...

Undoped InAs and p-n junction epitaxial layers were grown on (100)-cut InP substrates with molecular beam epitaxy. The lattice difference between the substrate was matched a graded AlInAs buffer layer. alloy composition, structural characteristics carrier mobility of structures determined from high-resolution x-ray diffraction, atomic force microscopy Hall-effect measurements, respectively. optical parameters characterized by emission terahertz (THz) pulses when samples illuminated...

Thin bismuth films of various thicknesses between 5 and 32 nm grown by molecular beam epitaxy on Si (111) substrates were investigated. The samples characterized the x-ray diffraction method, which allowed us to identify two types Bi crystallographic structures—α β bismuth. Terahertz radiation pulses emitted from after their illumination femtosecond optical with different wavelengths characterized. main THz emission features similar for both layers. Due 2D confinement, electron energy band...

<title>Abstract</title> Terahertz photoconductive switch antennas come in many designs that appear to be hardly ever sensibly selected. The femtosecond laser induced carriers generate a continuum at terahertz frequencies require low Q factor antenna design achievable through ohmic losses. On the one hand, if broadband spectrum is desired, simple coplanar stripline configuration with narrow arm width, i.e. short dipole, sufficient. other practical resonance effect raises fabrication and...

This study investigates the emission and spectral characteristics of photoconductive THz switches employing coplanar stripline contact geometries fabricated on a GaAs substrate. The experimental results reveal how power outputs as well shape are significantly influenced by strip width dimension. Utilizing Drude–Lorentz conductivity model, photocarrier dynamics were analyzed through an RLC circuit framework, offering insights into design influences response. Our findings suggest that matching...

The wurtzite phase catalyst-free InAs nanowires were investigated under femtosecond laser pulse photoexcitations. It was found that the THz radiation emission mechanisms depend on an exciting beam polarization, namely, plasma oscillations for perpendicular to nanowire optical electric fields, and ballistically moving carrier separation parallel polarization fields. energetic distance between Γ7c Γ8c conduction bands experimentally determined be 0.5 eV.

Electron dynamics in the polycrystalline bismuth films were investigated by measuring emitted terahertz (THz) radiation pulses after their photoexcitation tunable wavelength femtosecond duration optical pulses. Bi grown on metallic Au, Pt, and Ag substrates electrodeposition method with Triton X-100 electrolyte additive, which allowed us to obtain more uniform consistent grain sizes any substrate. It was shown that THz are generated due spatial separation of photoexcited electrons holes...

Microscopic origin of THz emission from femtosecond laser excited narrow gap semiconductor surfaces is explained in terms the photoelectron ballistic movement non-parabolic and anisotropic conduction band. It has been shown that azimuthal angle dependences this are caused by lateral photocurrent component resulting anisotropy. A strong radiation was observed lower symmetry crystal planes illuminated along their surface normal, which allowed to demonstrate experimentally user-friendly...

Terahertz radiation pulses emitted after exciting semiconductor heterostructures by femtosecond optical were used to determine the electron energy band offsets between different constituent materials. It has been shown that when photon is sufficient enough excite electrons in narrower bandgap layer with an greater than conduction offset, terahertz pulse changes its polarity. Theoretical analysis performed both analytically and numerical Monte Carlo simulation polarity inversion caused are...

Microscopical models of surface THz emission from narrow-gap semiconductors are proposed; the experimental study reveals potential such emitters for their applications in THz-TDS systems.

Utilization of sources generating short optical pulses requires techniques for the monitoring temporal characteristics pulses. The is often performed by an interferometric autocorrelation technique with detectors which possess higher-order nonlinearity. In and mid-infrared spectral domains, one employs quadratic detection exploiting two-photon absorption or sum-frequency generation. THz frequency domain, finding convenient pulsed remains to be a challenge. One option quantum-engineered...