Spontaneous emission in microcavities formed by 2D photonic crystals

We studied modification of the spontaneous emission rate in the dielectric resonant cavities formed by a defect in a photonic bandgap material. A photonic bandgap structure is fabricated by drilling a triangular array of holes in a thin slab of III-V semiconductor using chemically assisted ion beam etching. The cavity is introduced by omission of one hole or by changing the shape of one or several holes. In such a structure the mode confinement on the wavelength scale is provided by total internal reflection in the vertical direction and by periodic modulation of the refractive index in the plane of the stucture. Since fabrication on the sub-micron scale introduces the surface quality problem, we also studied nonradiative surface recombination properties on the material's surfaces. Three-dimensional finite difference in time domain calculations were employed with Bloch boundary conditions to determine the band structure of the photonic band gap material, and then to model the field distribution and quality factor of semiconductor microcavities with photonic crystals. We showed that a few layers of PBG material provide a cavity Q higher than the Q of optoelectronic materials (typically 20).