Characterization of Sputtered CdTe Thin Films with Electron Backscatter Diffraction and Correlation with Device...

Area of Science:

• Materials Science
• Solid-State Physics
• Photovoltaics

Background:

• Polycrystalline CdTe thin film performance is linked to grain boundary density and size.
• The electrical impact of grain boundaries in CdTe films remains unclear, potentially affecting device performance positively, negatively, or neutrally.

Purpose of the Study:

• To investigate the relationship between microstructure and performance in sputtered CdTe films.
• To characterize grain size, boundary structure, and texture before and after CdCl2 treatment.

Main Methods:

• Electron backscatter diffraction (EBSD) was employed for microstructural characterization.
• CdTe films were sputtered at varying pressures and treated with CdCl2.
• Solar cell efficiency was correlated with microstructural parameters.

Main Results:

• As-deposited films showed weak fiber textures, with (111) at low pressures and (110) at high pressures.
• CdCl2 treatment induced significant grain recrystallization and a high proportion of twin boundaries.
• Solar cell efficiency correlated well with twin-corrected grain size, but not when twin boundaries were included as general grain boundaries.

Conclusions:

• Twin boundaries in CdTe films appear to be electrically neutral regarding recombination and carrier transport.
• Accurate microstructural analysis, distinguishing twin boundaries, is crucial for understanding and optimizing CdTe photovoltaic performance.