Near bulk-limited R 0 A of long-wavelength infrared type-II In As ∕ Ga Sb superlattice photodiodes with polyimide surface passivation

Effective surface passivation of type-II In As ∕ Ga Sb superlattice photodiodes with cutoff wavelengths in the long-wavelength infrared is presented. A stable passivation layer, the electrical properties of which do not change as a function of the ambient environment nor time, has been prepared by a solvent-based surface preparation, vacuum desorption, and the application of an insulating polyimide layer. Passivated photodiodes, with dimensions ranging from 400 × 400 to 25 × 25 μ m 2 , with a cutoff wavelength of ∼ 11 μ m , exhibited near bulk-limited R 0 A values of ∼ 12 Ω cm 2 , surface resistivities in excess of 10 4 Ω cm , and very uniform current-voltage behavior at 77 K .