Substrate-dependent morphology and raman response of InSe nanoparticles synthesized by laser ablation in liquid

Indium selenide (InSe) nanoparticles were synthesized via pulsed laser ablation in liquid (LAL) by ablating a bulk InSe target in distilled water using a Nd:YAG laser (1064 nm, ~ 10 ns, ~ 135 mJ, 10 Hz) for ~ 10 min, yielding a surfactant-free colloidal dispersion. A key aspect of this study is the systematic evaluation of substrate-dependent morphology and spectroscopic response, which has received limited attention for LAL-synthesized layered chalcogenides. The as-prepared colloid was drop-cast onto three substrates—carbon (C), quartz/glass, and crystalline silicon (Si)—to evaluate substrate-dependent morphology and spectroscopic visibility under identical preparation conditions. Scanning electron microscopy (SEM) revealed granular nanoparticle layers with substrate-dependent aggregation and lateral size distributions in the approximately 60–220 nm range; the mean particle/aggregate sizes extracted from SEM statistics were ~ 129 nm (C), ~ 87 nm (quartz/glass), and ~ 107 nm (Si). Energy-dispersive X-ray spectroscopy (EDX) and elemental mapping confirmed the presence and spatial co-distribution of In and Se on all substrates, while C, Si, and O signals were attributed to substrate/background contributions and partial surface oxidation typical for thin dried nanoparticle films. Raman spectroscopy (633 nm excitation, 1800 lines/mm grating) provided phase-sensitive verification of the InSe vibrational fingerprint in the 100–260 cm⁻ 1 region across the three substrates; a reproducible InSe band near approximately 253–254 cm⁻ 1 was consistently observed, indicating preservation of InSe vibrational characteristics after LAL synthesis. UV–Vis absorption spectroscopy of the colloidal dispersion further confirmed the optical response of the LAL-synthesized InSe nanoparticles. These findings provide insight into substrate-dependent spectroscopic behavior of LAL-synthesized layered semiconductors and highlight the importance of substrate selection for reliable morphological and spectroscopic characterization.