Modification of spontaneous emission in photonic crystals

The modification of spontaneous emission in a semiconductor photonic crystal and in a semiconductor microcavity at room temperature is the subject of this thesis. The broad spectral linewidth of semiconductors together with large surface recombination velocities make the observation of these effects an interesting and challenging task.; A quantum electrodynamical model is used to estimate enhancement of spontaneous radiation rates in photonic crystals and microcavities. Extensive numerical computations were employed to calculate the band structure of thin slab photonic crystals and the properties of microcavities. The minimal achievable effective mode volume, a crucial parameter for cavity enhancement of spontaneous emission was shown to be ≈2(λ/2n)3 where λ is the resonant wavelength and n is the refractive index. Five-fold enhancement of spontaneous emission was shown to be physically possible in InGaAs nanocavities.; Photoluminescence measurements of surface recombination velocity were used in the search of material system most suitable for fabrication of such a photonic crystal. The InGaAs and InGaN material systems were shown to be good candidates for luminescent photonic bandgap structures.; Angular resolved photoluminescence measurements were used to experimentally measure the band structure of so-called electromagnetic conduction bands of such a photonic crystal.; The enhancement of spontaneous emission extraction from a thin slab photonic crystal was demonstrated. It was shown that emission into the leaky bands of the photonic crystal has the same benefit as cavity-enhanced spontaneous emission, provided these bands are flat enough relatively to the spectral emission bandwidth of the material. Recommendations for novel LED designs were worked out based on the results of this study.