GaInNAsSb based solar cell structure has been grown using atomic hydrogen assisted molecular beam epitaxy (H-MBE). Transient photocapacitance (TPC) spectroscopy was applied to investigate the optically active defects in the Si-doped GaInNAsSb layer (n-GaInNAsSb) of the structure. In addition to the interband transitions, a sub-band-gap optical transition was also determined using TPC spectroscopy. This sub-band-gap transition corresponds to an electron trap (OE1) at 0.78 eV below the conduction band (E-C) edge of n-GaInNAsSb material. Thermally active defects were probed by the electrical measurement using admittance spectroscopy. Thus, a defect profile in the entire band gap of the n-GaInNAsSb film was obtained. (c) 2013 Elsevier B.V. All rights reserved.