1. Room-temperature nonradiative recombination lifetimes in c-plane Al1−xInxN epilayers nearly and modestly lattice-matched to GaN (0.11 ≤ x ≤ 0.21).
- Author
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Li, L. Y., Shima, K., Yamanaka, M., Egawa, T., Takeuchi, T., Miyoshi, M., Ishibashi, S., Uedono, A., and Chichibu, S. F.
- Subjects
CHARGE carrier lifetime ,QUANTUM efficiency ,DISLOCATION density ,OPTOELECTRONIC devices ,MOLE fraction - Abstract
Lattice-matched Al
1−x Inx N / GaN heterostructures with InN mole fraction (x) of 0.18 have attracted considerable interest for use in GaN-based optoelectronic devices. Because the light emission efficiency (η emission ) of Al1−x Inx N alloys is far less than that of Inx Ga1−x N, understanding its causes is essential. For this purpose, room-temperature photoluminescence lifetime (τ PL RT ), which almost represents the nonradiative recombination lifetime that limits the internal quantum efficiency in low η emission semiconductors, of c-plane Al1−x Inx N epilayers nearly and modestly lattice-matched to GaN (0.11 ≤ x ≤ 0.21) was examined. For the epilayers grown on low threading dislocation density (TDD) GaN substrates (≪ 10 7 c m − 2 ), τ PL RT principally decreased with increasing x, indicating a progressive increase in the concentration of nonradiative recombination centers (NRCs), N NRC . One of the probable causes is the growth temperature (T g ) reduction that is indispensable to incorporate more In, because in insufficient T g regime higher T g is preferred for enhancing the surface migration of adatoms to decrease the concentrations of vacancies that compose NRCs. The Al1−x Inx N epilayers of the same x but grown on high TDD (> --> 10 8 c m − 2 ) GaN-on-sapphire templates exhibited shorter τ PL RT . Because the diffusion length of minority carriers was nearly zero in the Al1−x Inx N epilayers, the shorter τ PL RT indicates higher bulk N NRC in high TDD epilayers. The Al1−x Inx N epilayers of considerably rough surface morphologies exhibited spatially inhomogeneous τ PL RT , implying that excited carriers recombined everywhere at InN-rich to InN-poor portions, where N NRC were likely lower to higher, respectively, than the average due to the deviations in the surface stoichiometry at various non-c-plane surfaces at a given T g . [ABSTRACT FROM AUTHOR]- Published
- 2022
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