Forming a Photoluminescent Layer on Another Surface in the Dark through Lasering of N-Type Silicon in an Electrolyte

Abstract

Photoetching of n-type silicon induces a photoluminescent (PL) layer containing nanocrystals on the irradiated surface, usually through band gap absorption (wavelength <1100 nm). Here, we demonstrate the formation of a PL layer restricted to the backside surface, not the irradiated surface, by using a 1064 nm Nd:YAG laser. A nanoscale structure of the PL layer is achieved by merely modifying the electrolyte concentration without adding oxidants. To illustrate the working principle, we submit the hypothesis of a quasi-pn structure based on the theory of a quasi-Fermi level. Because of the “injection current” effect due to the quasi-pn structure, the hole current promoted by free-carrier absorption flows toward the backside surface, leading to anodization. This result is remarkable because anodization of n-type silicon is very hard to achieve with just an etchant in the dark.

Utilization of Low Wavelength Laser Linking with Electrochemical Etching to Produce Nano-Scale Porous Layer on p-Type Silicon Wafer with High Luminous Flux

“…This porous silicon layer, which was in nano-scale, had good photoluminescence effect. 15,[26][27][28][29][30] Figure 7a shown the cross section image to analysis the porous size by imageJ analytical tool. Figure 7b shown the uniform distribution of the nano porous (average size of 6-10 nm).…”

“…Those resultants are better than that of porous silicon for the 2 mW laser power, the luminous flux value was 115 lm for 633 nm laser and 45 lm for 830 nm laser with an etching time of 5 min. 30 Cantore et al 31 reported that GaN shown the luminous flux of 1100 lm at a laser power 14550 mW for source of YAG: Ce at wavelength of 568 nm. Latynina et al 32 reported that Ce, Gd: Y 3 Al 5 O 12 revealed the luminous flux of 173 lm at a laser power 1270 mW for wavelength of 455 nm.…”