Micro-cavity light emitting diodes

Abstract

This chapter describes the basic theory of planar micro-cavity light emitting diodes and derives a number of design rules for high efficiency. The point source emits rays, or plane waves, with uniform power density in all directions. As in the scalar case, any field in a uniform layer can be decomposed into plane waves. In the vectorial case these plane waves have a polarisation, i.e. a particular time evolution of the E-field orientation. It obviously depends strongly on the position of the point source and leads to a similar conclusion as in the single mirror case: the radiated emission in a particular direction is high if the standing wave field strength at the point source is high. In reality we do have to consider a vectorial electromagnetic problem with vectorial fields and vectorial sources. In planar cavities one can basically make use of two types of mirrors: metallic mirrors or multilayer dielectric mirrors.