Anisotropic polarization of non‐polar GaN quantum dot emission

Abstract

We report on experimental and theoretical studies of the polarization selection rules of the emission of non‐polar GaN/AlN self‐assembled quantum dots. Time‐integrated and time‐resolved photoluminescence measurements have been performed to determine the degree of polarization. It is found that the emission of some samples can be predominantly polarized parallel to the wurtzite c axis, in striking difference with the previously reported results for bulk GaN and its heterostructures, in which the emission was preferentially polarized perpendicular to the c axis. Theoretical calculations based on an 8‐band k·p model are used to analyze the relative importance of strain, confinement and quantum dot shape on the polarization selection rules. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Reversed polarized emission in highly straineda-plane GaN/AlN multiple quantum wells

“…Combined Raman scattering, transmission electron microscopy ͑TEM͒ and x-ray diffraction ͑XRD͒ studies reveal out-of-plane expansion as high as 1.5%, comparable to those reported for a-plane QDs in Ref. 15. These strain values are significantly larger than in previously studied GaN QWs and films, characterized by strains in the 0.04-0.4 % range.…”

“…6,[11][12][13] Most notably, a preferential polarization of the spontaneous emission parallel to the wurtzite c axis has been reported in a-plane QD superlattices. 15 This results in a negative degree of polarization that has been ascribed to the combined effect of large values of strain and anisotropic confinement due to the elongated shape of the QDs.…”

A study of the piezoelectric properties of semipolar 112̅2 GaN/AlN quantum dots

“…Similar results were obtained in the case of GaN/AlGaN QD nanostructures where, in the semipolar case, the PL emission is strongly shifted toward the UV with simultaneous reduction of the PL peak (at full width at half maximum) compared to the polar ones as a result of the reduction of the QCSE . On an alternative substrate, asymmetric nonpolar GaN/AlN QDs grown on 6H‐SiC exhibited a preferential polarization of the emission (). Reduced electric field and reduced radiative lifetime GaN/AlGaN QWs and QDs have also been reported .…”