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Effect of surface roughness and H-termination chemistry on diamond's semiconducting surface conductance

April 10, 2017
  |
Journal Article
Author:
Travis C. Wade
…
Published in:
Diamond Related Mater., Vol. 76, 1 June 2017, pp. 79-85.
Topic:
advanced materials
R&D area:
R&D group:

Summary

The H-terminated surface of diamond when activated with NO2 produces a surface conduction layer that has been used to make FETs. Variations in processing can significantly affect this conduction layer. This article discusses the effect of diamond surface preparation and H termination procedures on surface conduction. Surface preparations that generate a rough surface result in a more conductive surface with the conductivity increasing with surface roughness. We hypothesize that the increase in conductance with roughness is the result of an increase of reactive sites that generate the carriers. Roughening the diamond surface is just one way to generate these sites and the rough surface is believed to be a separate property from the density of surface reactive sites. The presence of C in the H2 plasma used for H termination decreases surface conductance. A simple procedure for NO2 activation is demonstrated. Interpretation of electrical measurements and possible alternatives to activation with NO2 are discussed. Using Kasu's oxidation model for surface conductance as a guide, compounds other than NO2 have been found to activate the diamond surface as well.
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Summary

The H-terminated surface of diamond when activated with NO2 produces a surface conduction layer that has been used to make FETs. Variations in processing can significantly affect this conduction layer. This article discusses the effect of diamond surface preparation and H termination procedures on surface conduction. Surface preparations that generate...

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Effect of surface roughness and H-termination chemistry on diamond's semiconducting surface conductance

Wafer-scale aluminum nanoplasmonic resonators with optimized metal deposition

April 28, 2016
  |
Journal Article
Author:
Vladimir Liberman
…
Published in:
ACS Photonics, Vol. 3, No. 5, 18 May 2016, pp. 796-805.
Topic:
photonics
R&D area:
R&D group:

Summary

Spectroscopic ellipsometry is demonstrated to be an effective technique for assessing the quality of plasmonic resonances within aluminum nanostructures deposited with multiple techniques. The resonance quality of nanoplasmonic aluminum arrays is shown to be strongly dependent on the method of aluminum deposition. Three-layer metal-dielectric-metal nanopillar arrays were fabricated in a complementary metal-oxide semiconductor (CMOS) facility, with the arrays of nanopillars separated from a continuous metal underlayer by a thin dielectric spacer, to provide optimum field enhancement. Nanostructures patterned in optimized aluminum, which had been deposited with a high temperature sputtering process followed by chemical mechanical planarization, display different resonance and depolarization behavior than nanostructures deposited by the more conventional evaporation process. Full plasmonic band diagrams are mapped over a wide range of incidence angles and wavelengths using spectroscopic ellipsometry, and compared for aluminum nanostructures fabricated with two methods. The resonators fabricated from optimized aluminum exhibit a narrower bandwidth of both plasmonic resonance and depolarization parameters, indicating a higher quality resonance due to a stronger localization of the electric field. The optimized wafer-scale aluminum plasmonics fabrication should provide a pathway towards better quality devices for sensing and light detection in the ultraviolet and blue parts of the spectrum.
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Summary

Spectroscopic ellipsometry is demonstrated to be an effective technique for assessing the quality of plasmonic resonances within aluminum nanostructures deposited with multiple techniques. The resonance quality of nanoplasmonic aluminum arrays is shown to be strongly dependent on the method of aluminum deposition. Three-layer metal-dielectric-metal nanopillar arrays were fabricated in a...

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Wafer-scale aluminum nanoplasmonic resonators with optimized metal deposition

Driven dynamics and rotary echo of a qubit tunably coupled to a harmonic oscillator

April 27, 2012
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Journal Article
Author:
Simon Gustavsson
…
Published in:
Phys. Rev. Lett., Vol. 108, No. 17, 27 April 2012, 170503.
Topic:
quantum
R&D area:
R&D group:

Summary

We have investigated the driven dynamics of a superconducting flux qubit that is tunably coupled to a microwave resonator. We find that the qubit experiences an oscillating field mediated by off-resonant driving of the resonator, leading to strong modifications of the qubit Rabi frequency. This opens an additional noise channel, and we find that low-frequency noise in the coupling parameter causes a reduction of the coherence time during driven evolution. The noise can be mitigated with the rotary-echo pulse sequence, which, for driven systems, is analogous to the Hahn-echo sequence.
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Summary

We have investigated the driven dynamics of a superconducting flux qubit that is tunably coupled to a microwave resonator. We find that the qubit experiences an oscillating field mediated by off-resonant driving of the resonator, leading to strong modifications of the qubit Rabi frequency. This opens an additional noise channel...

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Driven dynamics and rotary echo of a qubit tunably coupled to a harmonic oscillator

CMOS-compatible dual-output silicon modulator for analog signal processing

July 21, 2008
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Journal Article
Author:
Steven Jay Spector
…
Published in:
Opt. Express, Vol. 16, No. 15, 21 July 2008, pp. 11027-11031.
Topic:
optics
R&D area:
R&D group:

Summary

A broadband, Mach-Zehnder-interferometer based silicon optical modulator is demonstrated, with an electrical bandwidth of 26 GHz and V[pi]L of 4 V·cm. The design of this modulator does not require epitaxial overgrowth and is therefore simpler to fabricate than previous devices with similar performance.
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Summary

A broadband, Mach-Zehnder-interferometer based silicon optical modulator is demonstrated, with an electrical bandwidth of 26 GHz and V[pi]L of 4 V·cm. The design of this modulator does not require epitaxial overgrowth and is therefore simpler to fabricate than previous devices with similar performance.

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CMOS-compatible dual-output silicon modulator for analog signal processing

Effect of carrier lifetime on forward-biased silicon Mach-Zehnder modulators

April 14, 2008
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Journal Article
Author:
Gui-Rong Zhou
…
Published in:
Opt. Express, Vol. 16, No. 8, 14 April 2008, pp. 5218-5226.
Topic:
optics
R&D area:
R&D group:

Summary

We present a systematic study of Mach-Zehnder silicon optical modulators based on carrier-injection. Detailed comparisons between modeling and measurement results are made with good agreement obtained for both DC and AC characteristics. A figure of merit, static VpiL, as low as 0.24Vmm is achieved. The effect of carrier lifetime variation with doping concentration is explored and found to be important for the modulator characteristics.
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Summary

We present a systematic study of Mach-Zehnder silicon optical modulators based on carrier-injection. Detailed comparisons between modeling and measurement results are made with good agreement obtained for both DC and AC characteristics. A figure of merit, static VpiL, as low as 0.24Vmm is achieved. The effect of carrier lifetime variation...

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Effect of carrier lifetime on forward-biased silicon Mach-Zehnder modulators

All silicon infrared photodiodes: photo response and effects of processing temperature

December 10, 2007
  |
Journal Article
Author:
Michael W. Geis
…
Published in:
Opt. Express, Vol. 15, No. 25, 10 December 2007, 87083.
Topic:
optics
R&D area:
R&D group:

Summary

CMOS compatible infrared waveguide Si photodiodes are made responsive from 1100 to 1750 nm by Si+ implantation and annealing. This article compares diodes fabricated using two annealing temperatures, 300 and 475C. 0.25-mm-long diodes annealed to 300C have a response to 1539 nm radiation of 0.1 A W-1 at a reverse bias of 5 V and 1.2 A W-1 at 20 V. 3-mm-long diodes processed to 475C exhibited two states, L1 and L2, with photo responses of 0.3 +/-0.1 A W-1 at 5 V and 0.7 +/-10.2 A W-1 at 20 V for the L1 state and 0.5 +/-0.2 A W-1 at 5 V and 4 to 20 A W-1 at 20 V for the L2 state. The diodes can be switched between L1 and L2. The bandwidths vary from 10 to 20 GHz. These diodes will generate electrical power from the incident radiation with efficiencies from 4 to 10 %.
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Summary

CMOS compatible infrared waveguide Si photodiodes are made responsive from 1100 to 1750 nm by Si+ implantation and annealing. This article compares diodes fabricated using two annealing temperatures, 300 and 475C. 0.25-mm-long diodes annealed to 300C have a response to 1539 nm radiation of 0.1 A W-1 at a reverse...

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All silicon infrared photodiodes: photo response and effects of processing temperature
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