arXiv subjects

Marcin Motyka

Publications and source records attributed to Marcin Motyka.

5 recordsLinked to original sources

arXiv2026

Resolving the band alignment of InAs/InAsSb mid-wave-infrared type-II superlattices

In this work, three InAs/InAs$_{0.65}$Sb$_{0.35}$ superlattices with different periods were investigated using photoluminescence and photoreflectance measurements and their band structure was simulated using a 14 bulk-band kp model. The structures were studied by analyzing the evolution of the spectral features in temperature and excitation power to determine the origin of optical transitions. After identifying which of these are related to the superlattice mini-bands, a rich collection of observed higher-order optical transitions was compared with refractive-index calculations. This procedure was used to adjust the parameters of the theoretical model, namely the bowing parameters of the InAsSb valence band offset and bandgap. It was also shown that the spectroscopy of the higher-order states combined with numerical modeling of the refractive index is a powerful tool for improvement of the material parameters, presenting a new approach to material studies of advanced semiconductor heterostructures.

cond-mat.mtrl-sci↗

arXiv2026

Experimental Demonstration of Plasmon-Enabled Monolithic Bragg Reflectors for Infrared Light via Inverse Design

High-reflectivity mirrors in the mid-infrared (MIR) range are essential for next-generation optoelectronic devices but are still constrained by strain accumulation, poor thermal conductivity, and growth instability of thick multi-alloy stacks in conventional distributed Bragg reflectors (DBRs). We introduce plasmon-enabled DBRs (PE DBRs) based on modulation-doped monolithic InP, where plasmonic dispersion in highly doped layers provides a strong refractive-index contrast. Using inverse-design optimization targeting reduced free-carrier absorption and maximized reflectivity, we demonstrate that PE DBRs can achieve reflectivities approaching 100%. Experimentally grown 14 {\mu}m thick InP PE DBRs exhibit up to 99% reflectance with bandwidths reaching 18% of the design wavelength. The monolithic, junction-free configuration ensures low resistivity and enhanced thermal performance, offering a scalable platform for efficient plasmonic mirrors in MIR photonics, with potential applications in photodetectors, light-emitting diodes and lasers.

physics.optics↗

arXiv2025

Large-Area Metal-Integrated Grating Electrode Achieving Near 100% Infrared Transmission

Highly transparent and conductive electrodes operating in the infrared (IR) are critically needed for a broad range of technologies, including light-emitting diodes, lasers and photodetectors, which are key building blocks of infrared cameras, LiDARs, and thermal systems such as IR heaters. While transparent conductive electrodes (TCEs) have seen substantial progress in the visible spectrum, their performance in the IR remains limited due to increased absorption and reflection caused by the plasma resonance of free carriers in conductive materials. Here, we demonstrate a large-area TCE based on a metal-integrated monolithic high-contrast grating (metalMHCG) fabricated on a GaAs substrate. This structure acts as an effective antireflection coating, achieving near-unity transmission of unpolarized mid- to far-infrared (M-FIR) light. The metalMHCG exhibits 94% transmission at a wavelength of 7 micrometers, corresponding to 135% relative to transmission through a flat GaAs-air interface, while maintaining an exceptionally low sheet resistance of 2.8 ohms per square. By simultaneously delivering excellent optical transparency and electrical conductivity, the metalMHCG establishes a new performance benchmark among M-FIR TCEs and provides a versatile platform for next-generation high-power optoelectronic devices.

physics.optics↗

arXiv2023

Monolithic High Contrast Grating Integrated with Metal: Infrared Electrode with Exceptionally High Conductivity and Transmission

The design of transparent conductive electrodes (TCEs) for optoelectronic devices requires a trade-off between high conductivity or transmittivity, limiting their efficiency. This paper demonstrates a novel approach to fabricating TCEs that effectively alleviates this trade-off: a monolithic GaAs high contrast grating integrated with metal (metalMHCG). The metalMHCG enables higher electrical conductivity than other TCEs, while providing transmissive and antireflective properties. We focus on infrared spectrum TCEs, which are essential for sensing, thermal imaging, and automotive applications. However, due to elevated free carrier absorption they are much more demanding than TCEs for the visible spectrum. We demonstrate 75% absolute transmittiance of unpolarized light, resulting in 108% transmittance relative to plain GaAs substrate. We achieved even larger absolute transmittance of polarized light, reaching 92% or 133% relative transmittance. Despite record high transmittance, the sheet resistance of the metalMHCG is several times lower than any other TCE, ranging from 0.5 to 1 Ohm/Sq.

physics.optics↗

arXiv2020

Electron-phonon coupling and a resonant-like optical observation of a band inversion in topological crystalline insulator Pb$_{1-x}$Sn$_x$Se

The optical reflectivity of Pb$_{0.865}$Sn$_{0.135}$Se and Pb$_{0.75}$Sn$_{0.25}$Se solid solutions was measured in the THz spectral region energetically corresponding to bulk optical phonon excitations and in the temperature range from 40 K to 280 K. The analysis of Pb$_{0.75}$Sn$_{0.25}$Se data performed within the dynamic dielectric function formalism revealed a new effect due to the electron-phonon coupling resulting in resonant changes of LO phonon frequency for energy gap equal to zero or to LO phonon energy. This effect is absent for Pb$_{0.865}$Sn$_{0.135}$Se that exhibits an open energy gap with trivial band ordering at all temperatures. These results show that reflectivity in the THz range constitute a versatile experimental method for precise determination of band inversion in narrow-gap topological materials. For Pb$_{0.75}$Sn$_{0.25}$Se the transition from trivial insulator to topological crystalline insulator phase takes place at temperature T$_0$ = (172 $\pm$ 2) K.

cond-mat.mtrl-sci↗