Epitaxial GaP grown on Silicon by MEE and MBE Techniques as a Pathway for Dilute Nitride-Si Tandem Solar Cells

Dilute nitride materials grown on Si offer a pathway for inexpensive, lattice matched multijunction solar cells. A comparison in device performance between two-terminal and three-terminal tandem solar cells with a dilute nitride top cell and a Si bottom cell was done by detailed-balance modelling. The hetero-integration of dilute nitrides on Si is an important part of realizing such a solar cell structure. Towards this end, a first key step is to optimize the growth of GaP on Si. In this work, the surface of GaP grown epitaxially on Si wafers of various orientations was studied using atomic force microscopy (AFM). Pits were observed on the GaP surface and showed an increase in feature size with higher growth temperatures.