Three-dimensional wavelength-scale confinement in quantum dot microcavity light-emitting diodes

The authors introduce a microcavity light-emitting diode (LED) structure that uses submicrometer oxide aperture and a quantum dot active region to achieve strong 3-dimensional confinement of both the carrier distribution and the optical field. Light-current curves show optical emission for devices >=400 nm in diam. Spectroscopy on elec. pumped LEDs, with apertures ranging from 2.5 down to 0.7 micro m, show several spectral lines corresponding to cavity modes. A strong blueshift of the resonant modes for smaller apertures demonstrates the role of the oxide aperture in confining laterally the optical wave in a vol. comparable to (l/n)3. Due to the high quality factors and low mode vols., the devices could be good candidates for the demonstration of the Purcell effect under elec. pumping. [on SciFinder (R)]