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Thermal emission of hydrogenated amorphous silicon microspheres in the mid-infrared

Journal article

R. Fenollosa and F. Ramiro-Manzano

International Journal of Thermal Sciences Volume 213 Article 109829 2025

Abstract

Hydrogenated amorphous silicon microspheres feature a pronounced phononic peak around 2000 cm-1 when they are thermally excited by means of a blue laser. This phononic signature corresponds to vibrational modes of silicon-hydrogen bonds and its emitted light can be coupled to Mie modes defined by the spherical cavity. The signal is apparently quite stable at moderate excitation intensities although there appeared some signs pointing to hydrides bonds reconfiguration and even hydrogen emission. Above a certain excitation threshold, a phase change from amorphous to poly-crystalline silicon occurs that preserves the good structural quality of the microspheres.

How to cite

Initials first

R. Fenollosa and F. Ramiro-Manzano. Thermal emission of hydrogenated amorphous silicon microspheres in the mid-infrared. Int. J. Therm. Sci. 213, 109829 (2025). DOI: 10.1016/j.ijthermalsci.2025.109829.

Family name first

Fenollosa, R., & Ramiro-Manzano, F. (2025). Thermal emission of hydrogenated amorphous silicon microspheres in the mid-infrared. International Journal of Thermal Sciences, 213, 109829. https://doi.org/10.1016/j.ijthermalsci.2025.109829

Article access and reuse

This is an open-access article published by Elsevier Masson SAS under the Creative Commons Attribution 4.0 International licence (CC BY 4.0). The figures below were extracted from the local article PDF without enlargement or reconstruction and are reproduced with attribution. The licence permits sharing and adaptation provided appropriate credit is given, the licence is linked and changes are indicated.

Figures

Original embedded field-emission scanning electron micrograph of a typical hydrogenated amorphous silicon microsphere with a one micrometre scale bar — **Figure 1.** Field Emission Scanning Electron Microscope (FESEM) image of a typical silicon microsphere utilized for thermal emission experiments.

Complete two-panel composition showing the thermal emission spectrum of an amorphous silicon microsphere and its corresponding interferogram — **Figure 2.** (a) Thermal emission spectrum of an amorphous silicon microsphere. (b) Corresponding interferogram.

Optical scattering spectra of an amorphous silicon microsphere before irradiation and after two successive irradiations — **Figure 3.** Optical scattering of an amorphous silicon microsphere performed before any irradiation and after two successive irradiations of 77 min for measuring the phonon emission of silicon hydrides.

Complete two-panel composition of emission spectra at increasing laser intensities and spectra illustrating the amorphous to polycrystalline phase change — **Figure 4.** (a) Emission spectra of an amorphous silicon microsphere at increasing laser excitation intensities from bottom-up. (b) Selected experimental spectra and a Mie-theory simulated emission spectrum illustrating the phase change.

Graph with complete left and right axes showing integrated emission intensity and peak centre versus laser intensity — **Figure 5.** Integral (black dots) and centre position (red dots) of the emission peak at 2000 cm-1 at different laser excitation intensities, corresponding to the spectra of Figure 4(a).

Complete two-panel composition comparing measured thermal emission spectra before and after phase transition with Mie-theory simulations — **Figure 6.** (a, b) Measured thermal emission spectra of two silicon microspheres before and after the amorphous-to-polycrystalline phase transition, with corresponding Mie-theory simulations.