Extended wavelength SWIR InGaAs focal plane array: Characteristics and limitations

•Extended wavelength InGaAs detectors MBE grown on InP substrate are demonstrated.•Dark current mechanisms in extended InGaAs detectors are studied.•InGaAs detector performance is determined by G–R and ohmic leakage mechanisms.•No tunneling component is observed at typical operating conditions.•We report extended InGaAs focal plane array with 2.6 μm cut-off.

We present the characteristics of large format (640 × 512) short wavelength infrared (SWIR) InGaAs photodetector focal plane array (FPA) with ∼2.65 μm room temperature cut-off wavelength. The detector epilayers were grown with solid source molecular beam epitaxy on InP substrates using a linearly graded InAlAs buffer layer. In spite of the large lattice mismatch, the FPA yields reasonably good responsivity nonuniformity (9%) with a pixel detectivity above 2 × 1010 cm Hz1/2/W at room temperature. The dark current of the pixels are dominated by generation–recombination (G–R) and shunt leakage mechanisms with negligible tunneling above 200 K up to a reverse bias voltage of 3 V. The results are very encouraging for further study toward the optimization of the epilayer structure and growth conditions in order to provide a lower cost technology alternative to HgCdTe in the SWIR band.