Glancing angle deposited CdTe: Nanostructured films and impact on solar cell performance

[摘要] Cadmium telluride (CdTe) thin films with different microstructures and optical properties have been produced on soda-lime glass by glancing angle deposition (GLAD) at oblique sputtering angles varying from 0 to 80 with respect to the substrate normal. From cross-sectional scanning electron micrographs, increasingly tilted columnar structure occurs with increasing incident angle for as-deposited CdTe films. CdTe films deposited at lower angles closer to normal incidence consist of a mixture of cubic zinc blende and hexagonal wurtzite crystal structures while films prepared at more oblique angles have hexagonal wurtzite crystal structure. Post-deposition CdCl2 treated films show enhancement in crystallite/grain size for samples prepared under all conditions. The optical response in the form of the complex dielectric function (epsilon = epsilon(1) + i epsilon(2)) spectra from 0.74 to 5.89 eV for the GLAD thin films are all qualitatively similar to single crystal CdTe. Higher angle deposited samples show columnar structure induced anisotropy in spectra in e in the transparent spectral range. Application of GLAD CdTe interlayers between CdS and CdTe of the standard CdS/CdTe heterojunction design solar cell shows better performance with up to 0.9% absolute efficiency increase.

[发布日期] 2020-01-15

[效力级别]  Proceedings Paper

[关键词] Glancing angle deposition;Dielectric function;Sputtering;CdTe solar cell;Anisotropy