1. Nitride Materials and Devices Project
Space Vacuum Epitaxy Center
University of Houston
NASA Commercial Space Center
Nitride Materials and Devices Project
Prof. Bensaoula:
Dr. Starikov:
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. Optical sensors are based on: Advantages of fluorescence:
Space Vacuum Epitaxy Center
University of Houston
NASA Commercial Space Center
Nitride Materials and Devices Project
Prof. Bensaoula:
Dr. Starikov:
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. Nitride Materials and Devices Project
Space Vacuum Epitaxy Center
University of Houston
NASA Commercial Space Center
Nitride Materials and Devices Project
Prof. Bensaoula:
Dr. Starikov:

4. Nitride Materials and Devices Project ECO-VSF Scattering Sensor
Space Vacuum Epitaxy Center
University of Houston
NASA Commercial Space Center
Nitride Materials and Devices Project
Prof. Bensaoula:
Dr. Starikov:
WetStar
Fluorometer
ECO-VSF Scattering Sensor
ECO Fluorometer

5. Advantages and potential sensor applications of III-V Nitrides
Space Vacuum Epitaxy Center
University of Houston
NASA Commercial Space Center
Nitride Materials and Devices Project
Prof. Bensaoula:
Dr. Starikov:
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. Nitride Materials and Devices Project Current project objectives:
Space Vacuum Epitaxy Center
University of Houston
NASA Commercial Space Center
Nitride Materials and Devices Project
Prof. Bensaoula:
Dr. Starikov:
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. Development and fabrication of LEDs
Space Vacuum Epitaxy Center
University of Houston
NASA Commercial Space Center
Nitride Materials and Devices Project
Prof. Bensaoula:
Dr. Starikov:
Development and fabrication of LEDs
and photodiodes integrated on a single substrate
UV power: ~466 W
Band: nm
Diameter: 0.6 mm
Reverse bias: 22 V

8. High resolution: m/Dm = 800
Space Vacuum Epitaxy Center
University of Houston
NASA Commercial Space Center
Nitride Materials and Devices Project
Prof. Bensaoula:
Dr. Starikov:
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: <1 ppm for
400msec scan
TOF-MS Cl2/Ar plasma spectra
TOF-MS BCl3/Ar plasma spectra

9. Advantages of III-V Nitrides growth on commercial silicon wafers
Space Vacuum Epitaxy Center
University of Houston
NASA Commercial Space Center
Nitride Materials and Devices Project
Prof. Bensaoula:
Dr. Starikov:
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. New objectives for the TSGC project continuation
Space Vacuum Epitaxy Center
University of Houston
NASA Commercial Space Center
Nitride Materials and Devices Project
Prof. Bensaoula:
Dr. Starikov:
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. Nitride Materials and Devices Project
Space Vacuum Epitaxy Center
University of Houston
NASA Commercial Space Center
Nitride Materials and Devices Project
Prof. Bensaoula:
Dr. Starikov:
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. Nitride Materials and Devices Project
Space Vacuum Epitaxy Center
University of Houston
NASA Commercial Space Center
Nitride Materials and Devices Project
Prof. Bensaoula:
Dr. Starikov:
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 R&D 100 award winner and is now operating at Argonne National Labs, University of North Carolina Chapel Hill, and University of Houston.

13. Nitride Materials and Devices Project
Space Vacuum Epitaxy Center
University of Houston
NASA Commercial Space Center
Nitride Materials and Devices Project
Prof. Bensaoula:
Dr. Starikov:
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. Nitride Materials and Devices Project
Space Vacuum Epitaxy Center
University of Houston
NASA Commercial Space Center
Nitride Materials and Devices Project
Prof. Bensaoula:
Dr. Starikov:
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