Photocapacitance study of MBE grown GaInNAsSb thin film solar cells

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 (EC) 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.

► GaInNAsSb based solar cell structure was grown using molecular beam epitaxy. ► Optically active defects were studied by transient photocapacitance spectroscopy. ► Deep optical level, OE1 was found at 0.78 eV below conduction band of GaInNAsSb. ► Thermally active defects, E1 and E2 were found by admittance spectroscopy. ► A complete defect profile in the Si-doped GaInNAsSb thin film has been obtained.