The effect of photocurrent amplification was observed in the type II isotype staggered-lineup N+-GaSb/n(0)-GaInAsSb single heterostructure. The illumination intensity influence to the gigantic photocurrent gain effect for applied bias voltage have been studied for this structures. A mechanism of photocurrent amplification in isotype GaSb/GaInAsSb structure due to hole confinement at the type II interface is observed, its magnitude being bias voltage and light intensity dependent. It is shown that the exponential dependence of the photocurrent on intensity confirm the photocurrent gain at small bias is due to modulation of a barrier transparency by the non-equilibrium holes trapped in the potential well in the type II interface as a previously predicted theoretically. (C) 2008 Elsevier B.V. All rights reserved.