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Photo‐induced absorption change for InGaN film by violet laser diode
Author(s) -
Nomura Masahiro,
Arita Munetaka,
Ashihara Satoshi,
Nishioka Masao,
Arakawa Yasuhiko,
Shimura Tsutomu,
Kuroda Kazuo
Publication year - 2004
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.200405026
Subject(s) - absorption (acoustics) , materials science , femtosecond , absorption edge , optoelectronics , excited state , laser , heterojunction , diode , optics , atomic physics , band gap , physics , composite material
We have investigated photo‐induced absorption changes for In 0.10 Ga 0.90 N multiple quantum wells and a thin film induced by a continuous‐wave (cw) beam and a femtosecond pulse in the violet region. For the thin‐film sample, nearly the same absorption changes were observed in cw pumping and pulse pumping measurements. Screening of the piezoelectric field in InGaN heterostructures causes absorption changes around the band edge. This screening results from spatial separation of electron–hole pairs to the opposite sides of the InGaN epilayer. These spatially separated carriers are trapped in deep levels and maintain the absorption changes. The trapped charges are considered to be thermally excited to the conduction band and diffuse to attain the equilibrium state. This process takes on the order of 100 μs and such a long decay time of absorption changes allows us to have large absorption changes even by low‐intensity cw pumping. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)