*Niva K Jayswal, Dipendra Adhikari, Indra Subedi, Corey R. Grice, Nikolas J. Podraza, University of Toledo, Toledo, OH
Glancing angle deposition (GLAD) radio frequency (RF) magnetron sputtering has been used to control the crystal structure and crystallite orientation of polycrystalline CdTe. In GLAD sputtering, substrate normal and target normal are at an oblique angle. At more oblique deposition angles, the hexagonal wurtzite phase of CdTe is produced. This wurtzite CdTe is used as an interlayer between the n-type hexagonal wurtzite CdS window layer and p-type cubic zinc blende CdTe absorber in the standard CdS/CdTe solar cell resulting in better lattice matching at the interlayer’s interface with hexagonal CdS and cubic CdTe and higher photovoltaic device performance. The optical and microstructural properties of the GLAD CdTe interlayer before and after CdCl2 treatment are obtained from spectroscopic ellipsometry (SE) and x-ray diffraction (XRD). Solar cells are fabricated with interlayers prepared under different oblique angle GLAD conditions and substrate temperature and compared to devices without the introduction of the GLAD CdTe interlayers. Improvements in PV device performance parameters including open circuit voltage, short circuit current, fill factor, and power conversion efficiency are related to GLAD CdTe interlayer characteristics.