The optical and electrical properties of InAs quantum dots epitaxially grown on a silicon substrate have been investigated to evaluate their potential as both photodiodes and avalanche photodiodes (APDs) operating at a wavelength of 1300 nm. A peak responsivity of 5 mA/W was observed at 1280 nm, with an absorption tail extending beyond 1300 nm, while the dark currents were two orders of magnitude lower than those reported for Ge on Si photodiodes. The diodes exhibited avalanche breakdown at 22 V reverse bias which is probably dominated by impact ionisation occurring in the GaAs and AlGaAs barrier layers. A red shift in the absorption peak of 61.2 meV was measured when the reverse bias was increased from 0 to 22 V, which we attributed to the quantum confined stark effect. This shift also leads to an increase in the responsivity at a fixed wavelength as the bias is increased, yielding a maximum increase in responsivity by a factor of 140 at the wavelength of 1365 nm, illustrating the potential for such a structure to be used as an optical modulator.
© 2012 OSA
(040.5160) Detectors : Photodetectors
(040.6040) Detectors : Silicon
(040.1345) Detectors : Avalanche photodiodes (APDs)
(250.0040) Optoelectronics : Detectors
(250.5590) Optoelectronics : Quantum-well, -wire and -dot devices
Original Manuscript: January 18, 2012
Revised Manuscript: February 17, 2012
Manuscript Accepted: February 17, 2012
Published: April 20, 2012
Quantum Dots for Photonic Applications (2012) Optical Materials Express
, "1300 nm Wavelength InAs Quantum Dot Photodetector Grown on Silicon," Opt. Express 20, 10446-10452 (2012)
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