PRECISELY TUNED EMISSION FROM POROUS SILICON VERTICAL OPTICAL CAVITY IN THE VISIBLE REGION

The operating peak energy of a porous silicon (PS) cavity can be compl etely controlled over a wide range of 1.5-2.2 eV, using a PS-based Fab ry-Perot resonator composed of a light-emitting active PS layer and tw o high-reflectivity mirrors. When the PS devices are excited by a uv l aser, quite narrow spectra (10-40 meV in full width at half-maximum) a re observed without any significant signs of side mode. The central ph oton energy is precisely and continuously tuned simply by changing the anodization parameters. The key issues of the controlled device opera tion are adjustment of the optical thickness of the active PS layer to an appropriate value and fabrication of the quarter-wavelength multil ayered PS mirror with a high reflectivity. The spectral qualities of t he emitted light are also discussed by theoretical analyses on the bas is of a simplified model. These results suggest that the PS devices op erate as sharp band-pass optical filter and the PS materials are avail able for novel silicon-based microphotonics. (C) 1996 American Institu te of Physics.