Polarization of emission from non-polar III-nitride quantum wells: the influence of confinement
Journal of Physics D: Applied Physics
Taking M-plane oriented GaN quantum wells (QW) as an example, it is shown that the finite out-of-plane crystal momentum arising from quantum confinement modifies valence band mixing in a way that can significantly alter the emission polarization properties of strained non-polar oriented wurtzite group III-nitride QWs. For certain values of strain, the emission polarization direction can rotate by 90 • either within the QW plane, or from being out-of-plane to being in-plane which is desirable
... ich is desirable for light emission applications. The study based on a k · p type perturbation theory simultaneously accounts for the influence of anisotropic in-plane strain which arises in such QWs and also affects the optical polarization properties. An important practical implication of these results is that M-plane oriented Al x Ga 1−x N QWs under anisotropic in-plane tensile strain can work as efficient ultra-violet light emitters, unlike bulk Al x Ga 1−x N films with identical composition and strain. After including the influence of the out-of-plane crystal momentum, the emission polarization criterion allows for larger concentration of Al in such QW active layers if the well width is kept sufficiently small. These results are also applicable to A-plane oriented QWs.