1. Abrupt dependence of ultrafast extrinsic photoconductivity on Er fraction in GaAs:Er.
- Author
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Brown, E. R., Mingardi, A., Zhang, W. -D., Feldman, A. D., Harvey, T. E., and Mirin, R. P.
- Subjects
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PHOTOCONDUCTIVITY , *ELECTRIC conductivity , *GALLIUM arsenide , *GALLIUM compounds , *NANOPARTICLES - Abstract
We present a study of room-temperature, ultrafast photoconductivity associated with a strong, sub-bandgap, resonant absorption around λ=1550nm in three MBE-grown GaAs epitaxial layers heavily doped with Er at concentrations of ≈2.9×1018 (control sample), 4.4×1020, and 8.8×1020 cm-3, respectively. Transmission-electron microscopy reveals lack of nanoparticles in the control sample, but abundant in the other two samples in the 1.0-to-3.0-nm-diameter range, which is consistent with the previously known results. We measure very high photoelectron (Hall) mobility (2.57×103 cm2/V-s) and terahertz power (46 μW average) in the 4.4×1020 sample, but then, an abrupt decay in these properties as well as the dark resistivity is seen as the Er doping is increased just 2 times. The Er doping has little effect on the picosecond-scale, 1550-nm photocarrier lifetime. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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