Effects of Barrier Width on Spectral Response of Strained Layer Superlattices for High Efficiency Solar Cells

Characteristics of strained layer superlattices (SLS) consisting of alternating layers In x Ga 1-x As and GaAs 1-y P y are examined for use in high efficiency solar cells. The effects of SLS quantum barrier widths on tunneling probability and short circuit current are discussed through analysis of J-V and spectral response measurements. Results indicate a threshold barrier thickness for which tunneling effects are deleterious. Effect of the number of SLS periods incorporated into a p-i-n structure and maximum number of periods are presented through spectral response and CV analysis. It is demonstrated that SLS show increasing responsivity with increasing number of periods due to higher absorption. CV analysis is performed to determine zero bias depletion widths for verifying appropriate number of SLS periods and fully depleted SLS region.