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.