The ultimate IRFPA might have the following desirable characteristics:
• operation at room temperature for all spectral bands,
• megapixels with ultrasmall pitch,
• diffraction-limited performance,
• fast, aberration-free optics,
• infinite unit cell well capacity with zero noise electrons,
• multicolor capability, and
• noiseless gain at moderate reverse bias - active/passive imaging.
Some of these characteristics are related to the limitations posed by
current silicon ROIC technology, some are related to the limitations of current optics design, and others are related to the limitations of the currently available IR detector architectures. It is of interest to consider the limitations on the performance of this ultimate IRFPA, given carte blanche with regard to the ROIC and optics requirements; i.e., we will assume that infinite well capacity is available with zero noise electrons, together with aberration-free, infinitely fast optics. The object of this exercise is to highlight the limitations on the major system performance parameters that are due solely to our choice of IR material and detector architecture. For analytical simplicity, we assume monocolor FPAs operating without avalanche gain and with a constant bandgap as a function of temperature. Issues associated with these assumptions will be discussed.
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