Near-infrared photodetectors based on Si/SiGe quantum nanostructures
Near-infrared photodetectors based on Si/SiGe quantum nanostructures
Si/Si1-xGex multiple quantum well structures are grown by low pressure chemical vapour deposition (LPCVD). The LPCVD systems used were built in-house and are used to produce expitaxial layers at relatively high growth rates. Typically, 10 periods of Si/Si1-xGex quantum wells are grown on <100> silicon substrates at 800°C and at 0.5 Torr. SiGe quantum wells of around 10, 20 or 30 nm are produced with Ge content in the range 6% to 20%. Increasing germane flow is shown to increase the incorporation rate of germanium atoms and at high germanium incorporation levels the Si/Si1-xGex layers are shown to form lens-shaped quantum dots of relatively high germanium content.
Absorption and photoluminescence (PL) measurements are performed to investigate the optical properties and the band structure of the quantum structures. Extended absorption in the near-infrared is observed for the Si/Si1-xGex quantum well samples, with a wavelength cut-off around 1300nm. Doped multi-layer samples indicate additional absorption in the 2μm to 5μm spectral range, due to a free carrier absorption mechanism. Photoluminescence spectra indicate bandgap narrowing due to both increasing germanium composition and strain effects, furthermore, free exciton radiative transitions are observed up to 100K indicating quantum confinement.
p-i-n photodiodes are constructed to form photodetectors incorporating Si/Si1-xGex epilayers. The epitaxial layers grown at 820°C and at 0.5 Torr, consisted sets of ten periods of Si/i1-xGex layers with nominal 6% or 20% germanium content and 10, 20 or 30 nm SiGe thickness providing six main device sets. The I-V characteristics of all devices indicate reliable diode performance. Device photoresponses were studied with a range of bias voltages for wavelengths from 900 to 1500 nm at room temperature. The quantum efficiency in all devices indicates good photodetection extending to 1350 nm in the near-infrared beyond the energy corresponding to the bandgap of silicon.
University of Southampton
Iamraksa, Phansak
1fb53167-1353-4412-9864-b94874868bb4
2006
Iamraksa, Phansak
1fb53167-1353-4412-9864-b94874868bb4
Iamraksa, Phansak
(2006)
Near-infrared photodetectors based on Si/SiGe quantum nanostructures.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
Si/Si1-xGex multiple quantum well structures are grown by low pressure chemical vapour deposition (LPCVD). The LPCVD systems used were built in-house and are used to produce expitaxial layers at relatively high growth rates. Typically, 10 periods of Si/Si1-xGex quantum wells are grown on <100> silicon substrates at 800°C and at 0.5 Torr. SiGe quantum wells of around 10, 20 or 30 nm are produced with Ge content in the range 6% to 20%. Increasing germane flow is shown to increase the incorporation rate of germanium atoms and at high germanium incorporation levels the Si/Si1-xGex layers are shown to form lens-shaped quantum dots of relatively high germanium content.
Absorption and photoluminescence (PL) measurements are performed to investigate the optical properties and the band structure of the quantum structures. Extended absorption in the near-infrared is observed for the Si/Si1-xGex quantum well samples, with a wavelength cut-off around 1300nm. Doped multi-layer samples indicate additional absorption in the 2μm to 5μm spectral range, due to a free carrier absorption mechanism. Photoluminescence spectra indicate bandgap narrowing due to both increasing germanium composition and strain effects, furthermore, free exciton radiative transitions are observed up to 100K indicating quantum confinement.
p-i-n photodiodes are constructed to form photodetectors incorporating Si/Si1-xGex epilayers. The epitaxial layers grown at 820°C and at 0.5 Torr, consisted sets of ten periods of Si/i1-xGex layers with nominal 6% or 20% germanium content and 10, 20 or 30 nm SiGe thickness providing six main device sets. The I-V characteristics of all devices indicate reliable diode performance. Device photoresponses were studied with a range of bias voltages for wavelengths from 900 to 1500 nm at room temperature. The quantum efficiency in all devices indicates good photodetection extending to 1350 nm in the near-infrared beyond the energy corresponding to the bandgap of silicon.
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Published date: 2006
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Local EPrints ID: 466162
URI: http://eprints.soton.ac.uk/id/eprint/466162
PURE UUID: 6de9ab0a-5a6c-42fb-bb22-e48534461cf3
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Date deposited: 05 Jul 2022 04:34
Last modified: 16 Mar 2024 20:32
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Author:
Phansak Iamraksa
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