The standard Schottky noise approach alone is not sufficient to describe the noise mechanism in an InAs/GaSb superlattice photodetector at reverse negative bias. The additional noise identified appears at surface activation energies below 60meV and is inversely proportional to the reverse bias. In order to satisfactorily explain the experimental data, we hereby propose the existence of a surface recombination noise that is a function of both the frequency and bias. The calculated noise characteristics indeed show good agreement with the experimental data. © 2013 The Japan Society of Applied Physics.