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Accession Number N20120016988
Title GaN-Based Detector Enabling Technology for Next Generation Ultraviolet Planetary Missions.
Publication Date Oct 2012
Media Count 2p
Personal Author C. Kotecki G. Gronoff S. Aslam S. Janz T. Hewagama
Abstract The ternary alloy AlN-GaN-InN system provides several distinct advantages for the development of UV detectors for future planetary missions. First, (InN), (GaN) and (AlN) have direct bandgaps 0.8, 3.4 and 6.2 eV, respectively, with corresponding wavelength cutoffs of 1550 nm, 365 nm and 200 nm. Since they are miscible with each other, these nitrides form complete series of indium gallium nitride (In(sub l-x)Ga(sub x)N) and aluminum gallium nitride (Al(sub l-x)Ga(sub x)N) alloys thus allowing the development of detectors with a wavelength cut-off anywhere in this range. For the 2S0-365 nm spectral wavelength range AlGaN detectors can be designed to give a 1000x solar radiation rejection at cut-off wavelength of 325 nm, than can be achieved with Si based detectors. For tailored wavelength cut-offs in the 365-4S0 nm range, InGaN based detectors can be fabricated, which still give 20-40x better solar radiation rejection than Si based detectors. This reduced need for blocking filters greatly increases the Detective Quantum efficiency (DQE) and simplifies the instrument's optical systems. Second, the wide direct bandgap reduces the thermally generated dark current to levels allowing many observations to be performed at room temperature. Third, compared to narrow bandgap materials, wide bandgap semiconductors are significantly more radiation tolerant. Finally, with the use of an (AI, In)GaN array, the overall system cost is reduced by eliminating stringent Si CCD cooling systems.
Keywords Aluminum alloys
Gallium alloys
Gallium nitrides
Indium alloys
Quantum efficiency
Semiconductors(Materials)
Ternary alloys
Ultraviolet detectors

 
Source Agency National Aeronautics and Space Administration
NTIS Subject Category 54C - Astrophysics
71 - Materials Sciences
Corporate Author Goddard Space Flight Center, Greenbelt, MD.
Document Type Conference proceedings
Title Note N/A
NTIS Issue Number 1316
Contract Number N/A

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