Photoluminescence investigation of ferromagnetic Ga 1− xMn xN layers with GaN templates grown on sapphire (0 0 0 1) substrates

Abstract

We have investigated the temperature and composition dependent photoluminescence (PL) spectra in Ga 1− x Mn x N layers (where x ≈ 0.1–0.8%) grown on sapphire (0 0 0 1) substrates using the plasma-enhanced molecular beam epitaxy technique. The efficient PL is peaked in the red (1.86 eV), yellow (2.34 eV), and blue (3.29 eV) spectral range. The band-gap energy of the Ga 1− x Mn x N layers decreased with increasing temperature and manganese composition. The band-gap energy of the Ga 1− x Mn x N layers was modeled by the Varshni equation and the parameters were determined to be α = 2.3 × 10 −4, 2.7 × 10 −4, 3.4 × 10 −4 eV/K and β = 210, 210, and 230 K for the manganese composition x = 0.1%, 0.2%, and 0.8%, respectively. As the Mn concentration in the Ga 1− x Mn x N layers increased, the temperature dependence of the band-gap energy was clearly reduced.