Space Vacuum Epitaxy Center

1
Space Vacuum Epitaxy Center University of
Houston NASA Commercial Space Center
Nitride Materials and Devices Project Prof.
Bensaoula bens_at_jetson.uh.edu Dr. Starikov
dstarikov_at_space.svec.uh.edu
Compact III-V Nitrides-Based Integrated
Multifunctional Optoelectronic Sensors for
Contaminant Characterization in Enclosed Space
Environments. A. Bensaoula, D. Starikov, I .
Berishev, N. Badi, N. Medelci, J.-W. Um, and A.
Tempez

• Outline
• Introduction
• Current Project objectives
• Results of the first 5 month work
• Objectives and goals for project continuation
• Preliminary results on Nitride materials growth
  on Si
• Conclusions
• Acknowledgements

2
Space Vacuum Epitaxy Center University of
Houston NASA Commercial Space Center
Nitride Materials and Devices Project Prof.
Bensaoula bens_at_jetson.uh.edu Dr. Starikov
dstarikov_at_space.svec.uh.edu

• Optical sensors are based on
• Absorption/Reflection (ppm)
• Scattering Turbidimetry (ppm), Nephelometry
  (ppb)
• Fluorescence/Phosphorescence/Luminescence (ppt)

• Advantages of fluorescence
• High sensitivity
• Simplicity
• High specificity
• Low cost
• Multifunctionality (detection, concentration,
  temperature, flow)

Laboratory type fluorescence system
3
Space Vacuum Epitaxy Center University of
Houston NASA Commercial Space Center
Nitride Materials and Devices Project Prof.
Bensaoula bens_at_jetson.uh.edu Dr. Starikov
dstarikov_at_space.svec.uh.edu
4
Space Vacuum Epitaxy Center University of
Houston NASA Commercial Space Center
Nitride Materials and Devices Project Prof.
Bensaoula bens_at_jetson.uh.edu Dr. Starikov
dstarikov_at_space.svec.uh.edu
WetStar Fluorometer
ECO-VSF Scattering Sensor
ECO Fluorometer
5
Space Vacuum Epitaxy Center University of
Houston NASA Commercial Space Center
Nitride Materials and Devices Project Prof.
Bensaoula bens_at_jetson.uh.edu Dr. Starikov
dstarikov_at_space.svec.uh.edu

• Advantages and potential sensor applications of
  III-V Nitrides
• UV applications (wide bandgap)
• Higher efficiency (direct band)
• Possibility to tune the band gap from 1.9 to
  6.2 eV (InGaN, AlGaN compounds)
• High thermal stability (up to 600 C)
• High mechanical and chemical stability

6
Space Vacuum Epitaxy Center University of
Houston NASA Commercial Space Center
Nitride Materials and Devices Project Prof.
Bensaoula bens_at_jetson.uh.edu Dr. Starikov
dstarikov_at_space.svec.uh.edu

• Current project objectives
• Development of compact integrated optoelectronic
  sensors based on III-V Nitrides grown by RF MBE
  for contaminants characterization
• Implementation of Ionwerks Time of Flight Mass
  Spectrometer for characterization of gaseous
  environments
• Integration of the optoelectronic sensor with
  the Time of Flight Mass Spectrometer for
  contaminants characterization of enclosed space
  environments

7
Space Vacuum Epitaxy Center University of
Houston NASA Commercial Space Center
Nitride Materials and Devices Project Prof.
Bensaoula bens_at_jetson.uh.edu Dr. Starikov
dstarikov_at_space.svec.uh.edu
Development and fabrication of LEDs and
photodiodes integrated on a single substrate
UV power 466 ?W Band 200- 400 nm
Diameter 0.6 mm Reverse bias 22 V
8
Space Vacuum Epitaxy Center University of
Houston NASA Commercial Space Center
Nitride Materials and Devices Project Prof.
Bensaoula bens_at_jetson.uh.edu Dr. Starikov
dstarikov_at_space.svec.uh.edu
Experiments with Time of Flight Mass Spectrometer
PA-RIE curve (red) is shifted for illustrative
purposes

• High resolution m/Dm 800
• 4 orders of magnitude of
• dynamic range,
• Low background
• Detection limit lt1 ppm for
• 400msec scan

TOF-MS Cl2/Ar plasma spectra
TOF-MS BCl3/Ar plasma spectra
9
Space Vacuum Epitaxy Center University of
Houston NASA Commercial Space Center
Nitride Materials and Devices Project Prof.
Bensaoula bens_at_jetson.uh.edu Dr. Starikov
dstarikov_at_space.svec.uh.edu

• Advantages of III-V Nitrides growth on commercial
  silicon wafers
• Much lower fabrication costs
• Compatibility with standard Si processing
  equipment
• Employment of Si-based junctions in the
  optoelectronic structure that can extend the
  spectral range into the visible and IR regions
• Possibility of integration with other
  silicon-based semiconductor devices or Micro
  Opto- Electro-Mechanical Systems (MOEMS)

10
Space Vacuum Epitaxy Center University of
Houston NASA Commercial Space Center
Nitride Materials and Devices Project Prof.
Bensaoula bens_at_jetson.uh.edu Dr. Starikov
dstarikov_at_space.svec.uh.edu

• New objectives for the TSGC project continuation
• Improve the epitaxial growth of III-V Nitrides
  on commercial silicon wafers
• Optimize the fabrication process of the
  optoelectronic structure grown on Si (growth,RIE,
  contact deposition)
• Evaluate characteristics of the fabricated
  fluorescence sensors (application range,
  sensitivity, dynamic range)
• Investigate possibilities of integration of the
  fluorescence sensors with other MOEMS developed
  on silicon

11
Space Vacuum Epitaxy Center University of
Houston NASA Commercial Space Center
Nitride Materials and Devices Project Prof.
Bensaoula bens_at_jetson.uh.edu Dr. Starikov
dstarikov_at_space.svec.uh.edu
Preliminary results on Nitride materials growth
on Si
I-V characteristic of a GaN/InGaN p-n
junction diode heterostructure grown on Si wafer
Spectral sensitivity of a GaN/InGaN diode
heterostructure grown on Si
12
Space Vacuum Epitaxy Center University of
Houston NASA Commercial Space Center
Nitride Materials and Devices Project Prof.
Bensaoula bens_at_jetson.uh.edu Dr. Starikov
dstarikov_at_space.svec.uh.edu

• Collaborators
• Ionwerks
• Ionwerks has over thirteen years experience in
  manufacturing and marketing a complete surface
  analysis systems including pulsed beam lines,
  vacuum hardware, and custom electronics. Recent
  additions to the product line have evolved from
  the research interests in TOF ion scattering and
  mass spectroscopy of recoiled ions (MSRI) which
  have been developed over the last several years.
  The new time of flight data and ion detector
  system was developed around a 4 channel
  Time-to-Digital Converter (TDC). In the fall of
  1996 the compony began marketing a novel
  reflectron ToF analyzer which is capable of
  performing surface analysis using both secondary
  ion mass spectroscopy (SIMS) and mass
  spectroscopy of recoiled ions (MSRI). All
  elements, including H, can be identified, with
  isotopic resolution using SIMS and MSRI. This
  instrument was recently named a 1997 RD 100
  award winner and is now operating at Argonne
  National Labs, University of North Carolina
  Chapel Hill, and University of Houston.

13
Space Vacuum Epitaxy Center University of
Houston NASA Commercial Space Center
Nitride Materials and Devices Project Prof.
Bensaoula bens_at_jetson.uh.edu Dr. Starikov
dstarikov_at_space.svec.uh.edu

• Conclusions
• Spectrally matched light emitting and
  photosensitive Schottky diode structures have
  been fabricated on a sapphire substrate
• Ionwerks TOF mass spectrometer exhibited high
  resolution, wide dynamic range, low background,
  and high sensitivity for measurements performed
  on BCl2/Cl2/Ar plasmas.
• Blue emission and photosensitivity have been
  observed on diode structures fabricated from
  Nitride material layers grown on a single
  commercial silicon wafer

14
Space Vacuum Epitaxy Center University of
Houston NASA Commercial Space Center
Nitride Materials and Devices Project Prof.
Bensaoula bens_at_jetson.uh.edu Dr. Starikov
dstarikov_at_space.svec.uh.edu

• Acknowledgements
• Texas Space Grant Consortium Program
• NASA cooperative agreement, NCC8-127
• Ionwerks NASA Phase II SBIR contact monitored
  by Mr. J. Watkins
• Environmental Institute of Houston, University
  of Houston
• Institute of Space Systems and Operations
• Texas Advanced Technology Program