Donor-related recombination processes in hydride-vapor-phase epitaxial GaN

Abstract

High-resolution, variable-temperature photoluminescence studies of recombination processes associated with excitons bound to donors in hydride-vapor-phase epitaxial GaN are presented. Detailed analyses of the two-electron satellite ͑2ES͒ region identify transitions associated with ground and excited states of both the donor-bound exciton complexes and of the donor itself. All of the 2ES transitions observed in this work can be accounted for by the recombination of excitons bound to Si and O substitutional impurities and the line positions are in excellent agreement with the energies of donor intraimpurity transitions measured previously by infrared absorption. Conflicting aspects of donor identification and the binding energies of impurities and excitons are clarified.

The electrical, optical, and structural properties of GaN epitaxial layers grown on Si(111) substrate with interlayers

“…In our case, the energy peak position of the D 0 X A transition redshifted by nearly 18 meV compared to the strain-free GaN template, which implies that there is a strong tensile stress that is present in the GaN epilayers grown on Si(111). The shoulder at 3.479 eV that was observed at the high energy side of the spectrum was attributed to the A-free exciton transition [27,28]. Additional defects related to weak blue luminescence (BL) and strong yellow luminescence (YL) peaks at 2.88 eV and 2.16 eV, respectively, were also observed at the low energy side of the PL spectra at 10 K. The YL is attributed to a shallow donor deep acceptor transition [29].…”

“…These types of transitions are commonly responsible for the dominant PL line in the n-type GaN grown by any technique on any substrate. In high-quality strain-free GaN samples with a low concentration of defects, the D 0 X A emission at 3.471 eV sometimes comprises two or more sharp lines, tentatively attributed to different shallow donors [27,28]. In our case, the energy peak position of the D 0 X A transition redshifted by nearly 18 meV compared to the strain-free GaN template, which implies that there is a strong tensile stress that is present in the GaN epilayers grown on Si(111).…”

Reply to “Comment on ‘Recombination of excitons bound to oxygen and silicon donors in freestanding GaN’ ”

“…We present a discussion of the intradonor transition energies and donor chemical shifts to avoid misunderstanding. In their Comment 1 on our publication, 2 Freitas, Moore, and Shanabrook ͑FMS͒ discuss differences between our paper 2 and the paper 3 by Freitas et al ͑FEA͒. The major difference between our analysis and that of FMS is in the assignment of the bound exciton recombination lines.…”

Magnetopolaron effect on shallow donors in GaN

“…This possibility has generated intensive studies of TES transitions in GaN. [16][17][18][19][20][21][22] Another D 0 X recombination process based on excitation in the final recombination state involves a simultaneous emission of a photon and a LO phonon. This process manifests itself in the PL spectrum by the appearance of a replica of the parent transition at an energy lower by a LO phonon energy.…”

“…In spite of many efforts, the final elemental identifications of the bound exciton lines in freestanding GaN are still under debate. 20,31 In far infrared spectroscopy ͑FIR͒, two dominant donors with binding energies equal to 30.16 meV and 33.2 meV have been identified as Si Ga and O N , respectively. 33 A consistency between intradonor transition energies provided by FIR spectroscopy and those obtained from the analysis of the twoelectron satellites can be obtained by assuming that the D 2 0 X A line involves the oxygen donor, and the D 3 0 X A line, the silicon donor.…”