Influence of the p-type doping on the radiometric performances of MWIR InAs/GaSb superlattice photodiodes

•T2SL photodiodes were grown with different designs and active zone thicknesses.•InAs-rich design was proposed to both reduce the dark current and increase the QE.•We study the influence of the active zone thickness on the QE spectrum.•We examine the influence of the p-type doping on the QE spectrum.•We study the influence of the SL design on the QE spectrum.

In this paper, quantum efficiency (QE) measurements performed on type-II InAs/GaSb superlattice (T2SL) photodiodes operating in the mid-wavelength infrared domain, are reported. Several comparisons were made in order to determine the SL structure showing optimum radiometric performances: same InAs-rich SL structure with different active zone thicknesses (from 0.5 μm to 4 μm) and different active zone doping (n-type versus p-type), same 1 μm thick p-type active zone doping with different SL designs (InAs-rich versus GaSb-rich and symmetric SL structures). Best result was obtained for the p-type doped InAs-rich SL photodiode, with a 4 μm active zone thickness, showing a QE that reaches 61% at λ = 2 μm and 0 V bias voltage.