Fabrication of visibly photoluminescent Si microstructures by focused ion beam implantation and wet etching

A technique is reported for the fabrication of optically active Si microstructures embedded in a crystalline Si (c-Si) substrate. The process combines Si microstructure fabrication by localized high dose Ga+ (1016/cm2) focused ion beam (FIB) implantation at 30 kV into n-type (100) Si followed by anisotropic etching in KOH:H2O (1:5 by volume). Self-selective porous Si (PoSi) formation of the microstructures is obtained by stain etching in HF:HNO3:H2O (1:3:5 by volume). Upon UV 365 nm or Ar+ 488 nm excitation, selective visible room-temperature photoluminescence (PL) was observed from the Si microstructures only. The PL, peaked at ∼670 nm with a full width at half-magnitude (FWHM) of ∼130 nm, is similar to that of PoSi obtained from c-Si substrate.