photodetectors based on laser-synthesized carbon nanofibers (CNFs) decorated with ultralow-concentration gold nanoparticles (AuNPs). Carbon nanostructures were prepared via pulsed laser ablation in liquid (LAL) using a Q-switched Nd:YAG laser (1064 nm), enabling morphology tuning by controlling the pulse without chemical additives or surfactants. To enhance photodetection performance, trace-level AuNPs (0.00001 mM) were integrated onto the CNFs surface, forming a CNFs@AuNPs/p-Si heterojunction. Structural and morphological analyses confirmed the formation of nanofibrous carbon networks with well-dispersed Au nanoparticles. Optical characterization revealed pulse-dependent band gap modulation and pronounced localized surface plasmon resonance (LSPR) of AuNPs. Electrical measurements demonstrated rectifying heterojunction behavior with significantly enhanced photocurrent under illumination. The hybrid CNFs@AuNPs device exhibited improved spectral responsivity (99.6 mA/W at 808 nm), high specific detectivity (1.59 × 10 13 cm·Hz 1 / 2 ·W⁻ 1 ), and external quantum efficiency exceeding 150%. The EQE values above 100% indicate a photoconductive gain mechanism, attributed to plasmon-assisted carrier generation, hot-electron injection from AuNPs, and extended carrier lifetime relative to transit time. Furthermore, the device showed fast and stable photoresponse with sub-second rise and fall times. The simultaneous enhancement of responsivity, detectivity, and temporal response at ultralow Au loading highlights the effectiveness of plasmon-induced carrier engineering in a simple laser-based platform. These results demonstrate a low-complexity, environmentally benign route for developing high-sensitivity carbon-based photodetectors for optoelectronic and sensing applications.
AL-Awsaj et al. (Fri,) studied this question.