CC BY
5Liquid-assisted laser texturing: a game-change technology toward
advanced Si optoelectronics
Yu. Borodaenko1*, S. Gurbatov1, A. Shevlyagin1, A. Kuchmizhak1'2
1-Institute of Automation and Control Processes, Far Eastern Branch, Russian Academy of Sciences,
5 Radio Str., Vladivostok, Russia 2- Pacific Quantum Center, Far Eastern Federal University, Vladivostok, Russia
Nanotextured silicon has emerged as paramount material in optoelectronics, significantly improving the performance of Si-based photodetectors and solar cell devices through optimization of light absorption and charge carrier transport characteristics [1]. Simple non-lithographic methods such as direct femtosecond laser patterning of silicon allows to create diverse self-organized surface morphologies spanning from periodic nanogratings (referred to as laser-induced periodic surface structures; LIPSS) [2] to random spiky structures. Nanostructures could improve photodetector devices [3], while their fabrication can be potentially upscaled at low cost through common CMOS technology. Here, using liquid-assisted fs-laser nanopatterning of silicon with nanogratings we demonstrated fabrication of advanced Si photodetectors (PD) with polarization-sensitive response (Figure 1). Moreover, laser-induced defect generation was also found to enhance the detector photoresponse at near-IR wavelengths (i.e. Si within transparency), while subsequent over-coating of its active areas with calcium disilicide allowed to construct hybrid devices for efficient photothermal-thermoelectric conversion with competitive performance [4,5].
This work was supported by Russian Science Foundation (grant. 23-49-10044).
Laser pulses 515 nm, 200 fs
Microscope objective
Quartz cuvette with methanol
Si wafer
laser-textured area
Photoresponse @ 850 nm
i) jst
180'
Random spikes
LIPSS 1 -1 V
EQEJ00%.....
LIPSS II
10
12 o
> ts
_j 10 2.
900 1100
Wavelength, nm
Fig. 1. (a) Schematically illustrated procedure of fs-laser nanotexturing of Si p-n junction in methanol. (b) Optical photograph of the fabricated p-n Si PD. SEM images (top view) of the (c) LIPSS and (d) spikes produced over Si surface. Insets: enlarged and tilted view of the corresponding morphologies. Scale bars on main and inset images correspond to 1 and 0.5 ^m, respectively. (e) Photoresponse as a function of polarization angle © of the incident 850-nm wavelength laser beam measured for Si PDs patterned with (e) LIPSS and (f) spike structures (the polarization is set perpendicular to the LIPSS nanotrenches at ©i=0°/180°). (f) Comparative photoresponse spectra of the Si PD patterned with LIPSS measured for cross-polarized pump radiation (©± and © nanotrenches) at -1 V bias voltage conditions, the red dashed line indicates the response of an ideal photodetector with 100% external quantum efficiency.
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[3] Y. Borodaenko, D. Pavlov, A. Cherepakhin, E. Mitsai, S. Gurbatov, S. Syubaev, A. Shevlyagin, A. Kuchmizhak, Liquid-Assisted Laser Nanotexturing of Silicon: Onset of Hydrodynamic Processes Regulated by LIPSS. Advanced Materials Technologies, 9(8), 2301567 (2024).
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[5] H. Cansizoglu, et al, Dramatically enhanced efficiency in ultra-fast silicon MSM photodiodes via light trapping structures, IEEE Photonics Technology Letters, 31, 1619-1622 (2019).
