16 research outputs found
Linear polarization of the photoluminescence of quantum wells
The degree and orientation of the magnetic-field induced linear polarization
of the photoluminescence from a wide range of heterostructures containing
(Cd,Mn)Te quantum wells between (Cd,Mn,Mg)Te barriers has been studied as a
function of detection photon energy, applied magnetic field strength and
orientation in the quantum well plane. A theoretical description of this effect
in terms of an in-plane deformation acting on the valence band states is
presented and is verified by comparison with the experimental data. We
attempted to identify clues to the microscopic origin of the valence band spin
anisotropy and to the mechanisms which actually determine the linear
polarization of the PL in the quantum wells subject to the in-plane magnetic
field. The conclusions of the present paper apply in full measure to
non-magnetic QWs as well as ensembles of disk-like QDs with shape and/or strain
anisotropy.Comment: 21 pages, 10 figure
Fabrication of GaN photonic crystals for 400 nm wavelength
We report on results of the fabrication and the micro-reflectance measurement of GaN photonic crystals. The etching performance of GaN has been studied with a conventional reactive ion etching system and SiCl4 plasma. We obtained an etch rate of 100 nm/min and etching depth of 600 nm for dense GaN pillars. With graphite lattice of 270 run period we observed a high reflection peak in the region of 400 nm wavelengths, depending strongly on the incident light polarization, which is in a good agreement with the theoretical calculation. (C) 2001 Elsevier Science B.V. All rights reserved
Equifrequency surfaces in GaN/sapphire photonic crystals
International audiencePhotonic crystals are a new class of materials where photonic band gaps, large dispersion and anisotropy occur. By exploiting these properties GaN photonic crystals should have important potential for optoelectronic applications, principally in the areas of high-efficiency light emitters and second-harmonic generators. We present measurements of the equifrequency surfaces of the radiative Bloch modes for a photonic crystal etched in a GaN/sapphire film. The photonic band structure is calculated by using a scattering matrix method that reproduces well the anisotropy of the equifrequency surfaces exhibited by the photonic crystal. (C) 2002 Elsevier Science B.V. All rights reserved