LUMINESCENCE FROM QUANTUM-WELLS ARRANGED WITHIN A MICROCAVITY

Detailed investigations are presented of photoluminescence spectra from two slightly different and wedge-shaped InGaAs quantum wells (QWs) positioned at the antinode and near the node of a GaAs lambda/2-cavity, where nlambda = lambda(O) is the emission wavelength in vacuum and n the refractive index. The measurements are performed at 5 K. Position dependences show energy shifts of the luminescence lines due to the intended shape of the QWs and a variation of the intensities. Angle dependences show distinct deviations from the cos2 - law of free dipol radiation as well as from the modified radiation pattern in a resonator. For an emission wavelength below the resonator mode the intensity peaks at a 30-degrees inclination from the surface normal. Investigations of the resonator's reflectivity reveal its sensitivity against absorption. Ellipsometric determination of the effective dielectric function results in the absolute reflectivity of the constituting Bragg reflectors up to 99.8 % at the stop-band. This proves the enhanced sensitivity of the resonator's optical response on tiny variations of the optical and geometrical parameters. The exact coincidence of the emitted wavelength and the resonator mode was not achieved for emission parallel to the surface normal, the emission is not phase correlated.