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Optical monitoring of nonequilibrium carrier diffusion in single crystalline CVD and HPHT diamonds under high optical excitation
Author(s) -
Ščajev P.,
Malinauskas T.,
Lubys L.,
Ivakin E.,
Nesladek M.,
Haenen K.,
Jarašiūnas K.
Publication year - 2011
Publication title -
physica status solidi (rrl) – rapid research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.786
H-Index - 68
eISSN - 1862-6270
pISSN - 1862-6254
DOI - 10.1002/pssr.201105186
Subject(s) - ambipolar diffusion , diffusion , materials science , excitation , electron mobility , charge carrier , absorption (acoustics) , scattering , band gap , analytical chemistry (journal) , molecular physics , optoelectronics , optics , chemistry , electron , physics , chromatography , quantum mechanics , composite material , thermodynamics
We report on a novel approach for the contactless, all‐optical study of ambipolar carrier diffusion in single‐crystalline diamond layers. Using interband two‐photon and single photon absorption (at 351 nm and 213 nm), we created a spatially‐modulated free‐carrier light‐induced transient grating and monitored the in‐plane carrier diffusion in a wide range of injected carrier densities (10 15 cm –3 to 10 18 cm –3 ) and temperatures (80 K to 800 K). A drastic decrease of the ambipolar diffusion coefficient from ∼50 cm 2 /s at low injections to 6–10 cm 2 /s at high ones was observed at room temperature and even stronger at lower temperatures. The modelling based on bandgap renormalization and electron–hole scattering provided a fit to the injection‐dependent diffusivity. The determined low‐injection ambipolar mobility data for CVD layer were found in a good agreement with electrical time‐of‐flight measurements. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)