This work investigates the potential of p-type InAs/GaSb superlattice for the fabrication of full mid-wave megapixel detectors with n-on-p polarity. A significantly higher surface leakage is observed in deep-etched n-on-p photodiodes compared to p-on-n diodes. Shallow-etch and two-etch-step pixel geometry are demonstrated to mitigate the surface leakage on devices down to 10 µm with n-on-p polarity. A lateral diffusion length of 16 µm is extracted from the shallow etched pixels, which indicates that cross talk could be a major problem in small pitch arrays. Therefore, the two-etch-step process is used in the fabrication of 1280 × 1024 arrays with a 7.5 µm pitch, and a potential operating temperature up to 100 K is demonstrated.

This work investigates the potential of InAs/GaSb superlattice detectors for the short-wavelength infrared spectral band. A barrier detector structure was grown by molecular beam epitaxy and devices were fabricated using standard photolithography techniques. Optical and electrical characterisations were carried out and the current limitations were identified. The authors found that the short diffusion length of ~1.8 µm is currently limiting the quantum efficiency (double-pass, no anti-reflection coating) to 43% at 2.8 µm and 200 K. The dark current density is limited by the surface leakage current which shows generation-recombination and diffusion characters below and above 195 K, respectively. By fitting the size dependence of the dark current, the bulk values have been estimated to be 6.57·10−6 A/cm2 at 200 K and 2.31·10−6 A/cm2 at 250 K, which is only a factor of 4 and 2, respectively, above the Rule07.