Single-photon negative feedback APD focal plane array with 2.2 um cutoff wavelength

For this SBIR program, we propose to demonstrate a solid state short-wave infrared (SWIR) detector technology with true single photon sensitivity with a cutoff wavelength of at least 2.2 um suitable for integration into large-format focal plane arrays (FPAs). Array pixel designs will include self-quenching negative feedback avalanche diode (NFAD) structures with demonstrated single photon response consisting of avalanche pulses providing effective gains of 10^5 to 10^6 charges. These NFAD avalanche pulses also provide extremely reproducible quantized charge packets characterized by charge excess noise of ~1.08. Extended wavelength response to 2.2 um will be achieved using a novel Type II superlattice absorber that is lattice-matched to InP. The ability to realize this extended wavelength response with an absorber lattice-matched to InP provides high material quality (i.e., low dark count rate) and facilitates the incorporation of best-in-class device design elements already proven for our InP-based single photon detectors operating in Geiger mode, such as the NFAD structures. This approach also ensures a rapid integration of these novel 2.2 um pixel designs into large-format arrays that leverage our past success in realizing high-performance arrays of Geiger-mode avalanche diodes as large as 128 x 32.