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The performance of AlGaN solar blind UV photodetectors: responsivity and decay time
Author(s) -
Cherkashinin G.,
Lebedev V.,
Wagner R.,
Cimalla I.,
Ambacher O.
Publication year - 2006
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.200565213
Subject(s) - responsivity , photocurrent , photodetector , photoconductivity , optoelectronics , electron , time constant , materials science , physics , electrical engineering , quantum mechanics , engineering
The responsivity and the decay time of AlGaN solar blind UV‐detectors have been studied. The photodetectors have shown a good spectral responsivity in a narrow spectral range (220 < λ < 300 nm) and a short time response with the best estimated characteristic time constant of τ ∼ 30 ms measured at room temperature. Possible mechanisms responsible for the persistent photoconductivity (PPC) effect in Al x Ga 1– x N ( x = 0.51) are analyzed. A shape of the spectral response as a function of the applied voltage is analyzed in the frameworks of the space‐charge limited current model. It has been shown that the main source of PPC is traps above the Fermi level. PPC occurs when the density of free carriers equals the density of the traps. The model attributing PPC to the spatial separation of the photoexcited electrons and holes by the macroscopic potential barrier is not supported by our photocurrent studies. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)