Near bulk-limited R0A of long-wavelength infrared type-II InAs∕GaSb superlattice photodiodes with polyimide surface passivation

Abstract

Effective surface passivation of type-II $\mathrm{In}\mathrm{As}∕\mathrm{Ga}\mathrm{Sb}$ 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 $400\times 400\text{to}25\times 25\mu {\mathrm{m}}^2$ , with a cutoff wavelength of $\sim 11\mu \mathrm{m}$ , exhibited near bulk-limited $R_{0}A$ values of $\sim 12\Omega {\mathrm{cm}}^2$ , surface resistivities in excess of ${10}^4\Omega \mathrm{cm}$ , and very uniform current-voltage behavior at $77\mathrm{K}$ .