Modified spontaneous emission properties of CdS quantum dots embedded in novel three-dimensional microcavities

Modified spontaneous emission properties in the presence of confined photon modes inside the three-dimensional (3-D) optical microcavities are demonstrated. Self-formed pyramidal-shaped semiconductor structures fabricated by selective-area growth technique are utilized as an optical microcavity in which discrete photon modes are generated. Noticeable modification of spontaneous emission from active layers embedded in microcavity structures is clearly observed in μ-PL spectra at room temperature. Almost perfect coincidence between enhanced photoluminescence peak wavelengths and the resonance modes inside microcavity is observed. Furthermore, Purcell factors calculated from the obtained Q values reach ∼9, which is inaccessible in the planar microcavities with only one-dimensional photon confinement normal to the layers. These results indicate that the effective coupling between electronic system and 3-D confined optical fields is realized by the achievement of present low-loss 3-D microcavities with small cavity volume Vc whose dimension is comparable with λ3.