The Stanford Photonics Research Center

March 14, 2009

For amorphous Si, nanopillars and nanocones have been fabricated by etching hydrogenated amorphous Si (a-Si:H) film with monolayer of monodisperse silica nanoparticles as mask. These a-Si:H nanostructures display greatly enhanced absorption over a large range of wavelengths and angles of incidence, due to suppressed reflection. The enhancement effect is particularly strong for a-Si:H NC arrays, which provide nearly perfect impedance matching between a-Si:H and air through a gradual reduction of the effective refractive index.  Solar cell measurement data will be discussed.
 
For CuIn(Ga)Se2, critical issues related to phase inhomogeneity, grain boundary and CuIn(Ga)Se2-CdS interface, strong dependence of performance on processing condition have been actively studied but controversial. My group has synthesized CuIn(Ga)Se2 nanowires, which provide well-defined nanoscale domains to study the above issues. We have had many interesting and surprising discoveries related to the issues. I will present our measurement data on single nanowire and film of nanowire solar cells and discuss how device performance is correlated with materials structure.