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Layer thickness dependent carrier recombination rate in HVPE GaN
Author(s) -
Jarašiūnas Kęstutis,
Malinauskas Tadas,
Nargelas Saulius,
Gudelis Vytautas,
Vaitkus Juozas V.,
Soukhoveev Vitali,
Usikov Alexander
Publication year - 2010
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.200983532
Subject(s) - materials science , sapphire , wafer , dislocation , picosecond , carrier lifetime , optoelectronics , epitaxy , layer (electronics) , diffusion , optics , silicon , nanotechnology , composite material , laser , physics , thermodynamics
We report on nonequilibrium carrier dynamics in a set of hydride vapor phase epitaxy (HVPE) GaN wafers of different thickness (11, 17, 41, 90, and 145 µm) grown on the (0001) c ‐plane sapphire substrates. Carrier lifetime τ R and diffusion length L D were determined by picosecond transient grating and free carrier absorption (FCA) techniques. The nonradiative recombination lifetime increased from 400 ps in the thinnest layer up to 25 ns in the thickest one, and L D varied from 0.24 to 1.9 µm, respectively. The τ R and L D values in the 145 µm‐thick HVPE layer are the largest ones reported up to now in bulk GaN at room temperature. The data provided a relationship τ R ∝ d 3/2 between the carrier lifetime and wafer thickness in ∼10–150 µm thickness range. The latter dependence indicated the dramatic decrease of threading dislocation density in the probed subsurface area of the studied wafers from 4 × 10 9 to ∼10 6 cm −2 .