In-plane polarization anisotropy of the spontaneous emission of M-plane GaN/(Al,Ga)N quantum wells

摘要

We study the in-plane polarization of wurtzite GaN/(Al, Ga)N multiple quantum wells. Identical M-plane (1100) and C-plane (0001) structures are grown by plasma-assisted molecular-beam epitaxy on γ-LiAlO_(2)(100) and 6H-SiC(0001), respectively. While the emission from the conventional 0001 oriented wells is isotropic within the growth plane, we observe a strong polarization anisotropy of over 90 for the M-plane sample. The luminescence is polarized normal to 0001 and shows no spectral shift with polarization angle, i.e., it originates solely from A excitons (p_(x) and p_(y) valence band states). The deviation of the polarization degree from unity is attributed to the mixing with p_(z) valence band states due to quantum confinement.