Comparison of the optical properties of Er3+ doped gallium nitride prepared by metalorganic molecular beam epitaxy (MOMBE) and solid source molecularbeam epitaxy (SSMBE)

We report on the luminescence properties of Er doped GaN grown prepared by metalorganic molecular beam epitaxy (MOMBE) and solid-source molecular beam epitaxy (SSMBE) on Si substrates. Both types of samples emitted characteri stic 1.54 mum PL resulting from the intra-4f Er3+ transition I-4(13/2)-->I- 4(15/2). Under below-gap excitation the samples exhibited very similar 1.54 mum PL intensities. On the contrary, under above-gap excitation GaN: Er (S SMBE) showed similar to 80 times more intense 1.54 mum PL than GaN: Er (MOM BE). In addition, GaN: Er (SSMBE) also emitted intense green luminescence a t 537 nm and 558 nm which was not observed from GaN: Er (MOMBE). The averag e Lifetime of the green PL was determined to be 10.8 mus at 15 K and 5.5 mu s at room temperature. A preliminary lifetime analysis suggests that the de crease in lifetime is mainly due to the strong thermalization between the H -2(11/2) and S-4(3/2) excited states. Nonradiative decay processes are expe cted to only weakly affect the green luminescence.