Epitaxial GaP Layers Grown on Si Substrates using Migration Enhanced and Molecular Beam Epitaxy
Chaomin Zhang1, Allison Boley2, Nikolai N Faleev1, David J. Smith2, Christiana B. Honsberg1
1Arizona State University, Ira Fulton School, Solar Power Lab, Tempe, AZ, United States
/2Arizona State University, Physics Department, Tempe, AZ, United States

This study compares the microstructure of  epitaxial  GaP/Si heterostructures grown using the migration-enhanced epitaxy (MEE) and molecular beam epitaxy (MBE) techniques.  High-resolution X-ray diffraction and cross-section transmission electron microscopy for thin (~50 nm) GaP layers grown by MEE indicated greatly improved crystallinity and much reduced defect density for off-cut Si wafers compared with precisely oriented Si wafers. Observations of MBE-grown GaP/Si samples grown with thicknesses ranging ~40 nm to 2 microns revealed very low defect densities for thin layers but substantial threading defects and much higher defect densities predominated in the thicker, almost fully relaxed structures. 

Area: Sub-Area 3.4 (Joint Areas 3, 5 and 7): Characterization of Single-Crystal III-V PV Materials and Devices