Photoreflectance studies of optical transitions in GaNPAs intermediate band solar cell absorbers.

Abstract Photoreflectance spectroscopy is used to study optical properties of GaNPAs for the intermediate band (IB) solar cell absorbers. The IB is created in GaNPAs by the incorporation of ~2% of N atoms and the required partial occupation of the intermediate band with electrons is realized by doping with Si donors. Undoped and p -type doped (Be doped) GaNPAs films are studied as a references. Observation of all three absorption bands: VB → IB (a transition between the valence band and the IB), VB → CB (a transition between the valence band and the conduction band), and IB → CB (a transition between the IB and the conduction band), demonstrate that n -type doped GaNPAs layers act as intermediate band solar cell absorbers. Highlights • Photoreflectance has been applied to study optical transitions in Si-doped GaNPAs:Si layers with the Intermediate Band partially occupied by electrons. • Optical transitions related to three absorption bands, have been identified in the PR spectra. • It has been shown that broadening and intensities of optical transitions strongly depend on the doping concentration. [ABSTRACT FROM AUTHOR]