Comparison of 1.9 eV InGaP front- and rear-junction solar cells grown on Si

In this work, we compare the performance of front-junction (FJ) and rear-heterojunction (RHJ) 1.9 eV InGaP solar cells grown on Si by molecular beam epitaxy (MBE). The RHJs had greater Voc than the FJs on Si, even with ~10 × higher threading dislocation density (TDD), indicating superior dislocation tolerance of the n-type absorber of the RHJ compared to the p-type absorber of the FJ. However, poor internal quantum efficiency (IQE) of the RHJ on Si due to insufficient diffusion length also limited cell efficiency. Based on modeling, a thinner RHJ absorber will greatly boost the short circuit current density (J
sc
), enabling high-performance InGaP RHJs for epitaxial III-V/Si solar cells.