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Spectral and Intensity Dependence of Spatially Resolved Two-Photon Conductivity defects on a GaAsP Photodiode



D L. Osborn, S R. Leone


mtosecond laser excitation through a near-field scanning optical microscope is used to study spatially resolved defects in the two-photon conductivity of a GaAs0.6P0.4 diffusion type photodiode. Two types of defects are observed when the photodiode is excited with femtosecond pulses below the bulk band gap. Photocurrent enhancement defects show a higher photocurrent than the surrounding areas and have an essentially one-photon power dependence. These defects are often correlated with pits in the photodiode surface. Photocurrent depression defects have the normal two-photon power dependence and are not usually associated with surface pits. Based on the low measured coverage of both defect sites, the performance of GaAsP in auto- and cross-correlators will be unaffected in most situations. A deviation in alloy stoichiometry, in which localized areas are rich in arsenic while poor in phosphorus, provides the most likely explanation for the origin of the enhancement defects. Depression defects are most plausibly attributed to recombination of carriers at acceptor traps generated by localized impurities or dislocations.
Journal of Applied Physics
No. 1


defect, gallium arsenide phosphide, laser, near field microscopy, photoconductivity, two-photon


Osborn, D. and Leone, S. (2001), Spectral and Intensity Dependence of Spatially Resolved Two-Photon Conductivity defects on a GaAsP Photodiode, Journal of Applied Physics (Accessed April 20, 2024)
Created December 31, 2000, Updated October 12, 2021