Nitride Materials and Devices Project Space Vacuum Epitaxy Center University of Houston NASA Commercial Space Center Nitride Materials and Devices Project Prof. Bensaoula: bens@jetson.uh.edu Dr. Starikov: dstarikov@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

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: bens@jetson.uh.edu Dr. Starikov: dstarikov@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

Nitride Materials and Devices Project Space Vacuum Epitaxy Center University of Houston NASA Commercial Space Center Nitride Materials and Devices Project Prof. Bensaoula: bens@jetson.uh.edu Dr. Starikov: dstarikov@space.svec.uh.edu

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: bens@jetson.uh.edu Dr. Starikov: dstarikov@space.svec.uh.edu WetStar Fluorometer ECO-VSF Scattering Sensor ECO Fluorometer

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: bens@jetson.uh.edu Dr. Starikov: dstarikov@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

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: bens@jetson.uh.edu Dr. Starikov: dstarikov@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

Development and fabrication of LEDs Space Vacuum Epitaxy Center University of Houston NASA Commercial Space Center Nitride Materials and Devices Project Prof. Bensaoula: bens@jetson.uh.edu Dr. Starikov: dstarikov@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

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

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: bens@jetson.uh.edu Dr. Starikov: dstarikov@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)

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: bens@jetson.uh.edu Dr. Starikov: dstarikov@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

Nitride Materials and Devices Project Space Vacuum Epitaxy Center University of Houston NASA Commercial Space Center Nitride Materials and Devices Project Prof. Bensaoula: bens@jetson.uh.edu Dr. Starikov: dstarikov@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

Nitride Materials and Devices Project Space Vacuum Epitaxy Center University of Houston NASA Commercial Space Center Nitride Materials and Devices Project Prof. Bensaoula: bens@jetson.uh.edu Dr. Starikov: dstarikov@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 R&D 100 award winner and is now operating at Argonne National Labs, University of North Carolina Chapel Hill, and University of Houston.

Nitride Materials and Devices Project Space Vacuum Epitaxy Center University of Houston NASA Commercial Space Center Nitride Materials and Devices Project Prof. Bensaoula: bens@jetson.uh.edu Dr. Starikov: dstarikov@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

Nitride Materials and Devices Project Space Vacuum Epitaxy Center University of Houston NASA Commercial Space Center Nitride Materials and Devices Project Prof. Bensaoula: bens@jetson.uh.edu Dr. Starikov: dstarikov@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