Time-resolved photoluminescence, positron annihilation, and Al 0.23Ga 0.77N/GaN heterostructure growth studies on low defect density polar and nonpolar freestanding GaN substrates grown by hydride vapor phase epitaxy

S. F. Chichibu, K. Hazu, Y. Ishikawa, M. Tashiro, H. Namita, S. Nagao, K. Fujito, A. Uedono

Research output: Contribution to journalArticlepeer-review

56 Citations (Scopus)

Abstract

Time-resolved photoluminescence (TRPL) and positron annihilation measurements, as well as Al 0.23Ga 0.77N/GaN heterostructure growth by metalorganic vapor phase epitaxy were carried out on very low defect density, polar c-plane and nonpolar m-plane freestanding GaN (FS-GaN) substrates grown by hydride vapor phase epitaxy. Room-temperature photoluminescence (PL) lifetime for the near-band-edge (NBE) excitonic emission of the FS-GaN substrates increases with increasing positron diffusion length (L +); i.e., decreasing gross concentration of charged and neutral point defects and complexes. The best undoped c-plane FS-GaN exhibits record-long L + being 116 nm. The fast component of the PL lifetime for its NBE emission increases with temperature rise up to 100 K and levels off at approximately 1.1 ns. The result implies a saturation in thermal activation of nonradiative recombination centers. The surface and interface roughnesses for a Si-doped Al 0.23Ga 0.77N/GaN/Al 0.18Ga 0.82N/GaN heterostructure are improved by the use of FS-GaN substrates, in comparison with the structure fabricated on a standard GaN template. The emission signals related to the recombination of a two-dimensional electron gas and excited holes are recognized for an Al 0.23Ga 0.77N/GaN single heterostructure grown on the c-plane FS-GaN substrate.

Original languageEnglish
Article number103518
JournalJournal of Applied Physics
Volume111
Issue number10
DOIs
Publication statusPublished - 2012 May 15

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Fingerprint

Dive into the research topics of 'Time-resolved photoluminescence, positron annihilation, and Al <sub>0.23</sub>Ga <sub>0.77</sub>N/GaN heterostructure growth studies on low defect density polar and nonpolar freestanding GaN substrates grown by hydride vapor phase epitaxy'. Together they form a unique fingerprint.

Cite this