@article{oai:repo.qst.go.jp:00080535,
 author = {Sato, Shinichiro and Deki, Manato and Watanabe, Hirotaka and Nitta, Shugo and Honda, Yoshio and Nishimura, Tomoaki and C. Gibson, Brant and D. Greentree, Andrew and Amano, Hiroshi and Ohshima, Takeshi and Sato, Shinichiro and Ohshima, Takeshi},
 issue = {10},
 journal = {Optical Materials Express},
 month = {Sep},
 note = {Wide bandgap semiconductors are increasingly important for bioimaging
applications, as they can possess good biocompatibility and host a large range of fluorescent defects spanning the visible to infrared. Gallium nitride is one promising host for photostable fluorophores. In particular, neodymium (Nd)-doped gallium nitride (GaN) shows bright near infrared fluorescence and narrow room temperature linewidth and is therefore a candidate material for fluorescent probes for bioimaging. To explore the conditions necessary to generate biomarkers based on Nd:GaN, this paper reports the room temperature photoluminescence (PL) properties of small ensembles of Nd ions implanted into nanoscale regions of GaN epilayers. The minimum volume of Nd-implanted GaN which can be optically detected in this study is about 8E+4 nm^3 and the minimum detected ensemble of Nd ions is about 4E3, although not all of implanted Nd ions activate as luminescence centers. We show from the PL excitation spectra that the strongest resonant excitation appears at 619
nm, attributed to the 4I9/2 → 4G5/2 (4G7/2) transition in the 4f-shell. We measure the luminescence lifetime to be several tens of microseconds. We also identify the presence of a different excitation mechanism from the resonant excitation when excited below 510 nm (above 2.43 eV).},
 pages = {2614--2623},
 title = {Optical properties of neodymium ions in nanoscale regions of gallium nitride},
 volume = {10},
 year = {2020}
}