Effect of indium composition on GaInNAsSb solar cells grown by atomic hydrogen-assisted molecular beam epitaxy

We focus to develop a technique to accurately control the compositions of GaInNAsSb films as a function of In molar fraction grown by atomic hydrogen-assisted RF molecular beam epitaxy (H-MBE). Secondary ion mass spectroscopy analysis shows that the N composition decreases monotonically with increasing In composition from 0 to 17%. The Sb composition also decreases with increasing In composition. The PL intensity of GaInNAsSb films increases by a factor of 2.3 - 2.5 for small In composition of 5 - 13% and the full-width at half-maximum (FWHM) is also improved. However, any higher In compositions degrade the PL intensity and FWHM is broadened. The internal quantum efficiency characteristics for GaIn_xN_yAsSb solar cells (x = 0, 0.045, 0.1, and y = 0.015 ~ 0.016) are improved by the introduction of In, and redshift of the absorption edge by 60 ~ 80 nm is obtained. The filtered current density > 870 nm is increased by adding In to GaNAsSb from 4.9 (In = 0%) to 6.2 mA/cm² (In = 10%), respectively.