Wang, H.-C.H.-C.WangTang, T.-Y.T.-Y.TangCHIH-CHUNG YANGMalinauskas, T.T.MalinauskasJara?iunas, K.K.Jara?iunas2018-09-102018-09-10201018626351http://www.scopus.com/inward/record.url?eid=2-s2.0-77955836280&partnerID=MN8TOARShttp://scholars.lib.ntu.edu.tw/handle/123456789/356652https://www.scopus.com/inward/record.uri?eid=2-s2.0-77955836280&doi=10.1002%2fpssc.200983455&partnerID=40&md5=3b719d47288b879c976982a7afcf838aWe report on photoelectrical and optical properties of the GaN layers overgrown on the columnar structure with diameter of columns varying from 250 to 600 nm. Excess carriers were injected to 2-ìm thick overgrown layer by an interference pattern of two picosecond laser beams at 355 nm. Carrier recombination and diffusion was monitored by time-resolved transient grating technique and provided 3-4 fold increase of carrier lifetime (up to ∼500 ps) with respect to that in the GaN template. Even stronger increase of carrier lifetime at excess carrier density of ∼1019 cm-3 was observed both in the overgrown layers and substrate and attributed to saturation of electron trapping centers by free carriers. A factor of 7-8 stronger time-integrated photoluminescence intensity (at 363 nm) also confirmed the increased structural quality of the overgrown layers, what correlated well with the enhanced electrical parameters. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA.Carrier recombination; GaN; MOVPE; Nanostructures; Photoluminescence; Time-resolved experimentsCarrier dynamics; Carrier recombination; Columnar structures; Electrical parameter; Electron trapping; Excess carriers; Free carriers; GaN; GaN layers; GaN template; Interference patterns; MOVPE; Picosecond laser; Structural qualities; Time-integrated photoluminescence; Time-resolved; Transient grating technique; Gallium alloys; Gallium nitride; Nanostructures; Optical properties; Photoluminescence; Carrier lifetimeconference paper10.1002/pssc.2009834552-s2.0-77955836280