Raman characterization and stress analysis of AlN:Er3+ epilayers grown on sapphire and silicon substrates

Raman spectra and resulting stress analyses were performed for two sets of erbium implanted aluminum nitride (AlN:Er3+) epilayers deposited by molecular-beam epitaxy (MBE) on (0 0 0 1) sapphire and (1 1 1) silicon substrates. The AlN:Er3+ epilayers were examined using Raman scattering at different temperatures revealing the presence of the allowed E2(high) and A1(LO) phonon modes. The E2(high) mode linewidths reflect the best qualities of the implanted and thermally annealed epilayers grown on silicon substrates compared with those grown on sapphire substrates. It was observed that relatively tensile stress existed in AlN:Er3+ epilayer grown on sapphire in contrast to a compressive stress present in the AlN:Er3+ epilayer grown on silicon as indicated by the observed E2(high) mode frequency shift and the broadening of the vibrational mode linewidth. The stress value was calculated. The temperature dependence of the E2(high) frequency and linewidth for the AlN:Er3+ epilayer grown on sapphire were theoretically modeled.