Theoretical study of a modulated pore approach to a photonic crystal of inverted diamond type

In this paper a photonic crystal (PC) approach to an inverted diamondlike structure with a large complete bandgap is introduced. We theoretically study the dispersion behavior of PCs being fabricated by modulating macroporous silicon. The widening of single narrow pores to air bulges of spherical or ellipsoidal shape follows the lattice sites in the diamond cell. We compile band structure calculations as a function of (i) the radius of the air spheres, (ii) the radius of the connecting pores, and (iii) of the shape (sphere/ellipsoid) of the air bulges. The degradation of the bandgap, caused by the remaining air pores, can be partially compensated by nonspherical air bulges of adapted size and eccentricity.