title: Grazing Incidence Cross-Sectioning of Thin-Film Solar Cells via Cryogenic Focused Ion Beam: A Case Study on CIGSe.
abstract: Cryogenic focused ion beam (Cryo-FIB) milling at near-grazing angles is employed to fabricate cross-sections on thin Cu(In,Ga)Se2 with >8x expansion in thickness. Kelvin probe force microscopy (KPFM) on sloped cross sections showed reduction in grain boundaries potential deeper into the film. Cryo Fib-KPFM enabled the first determination of the electronic structure of the Mo/CIGSe back contact, where a sub 100 nm thick MoSey assists hole extraction due to 45 meV higher work function. This demonstrates that CryoFIB-KPFM combination can reveal new targets of opportunity for improvement in thin-films photovoltaics such as high-work-function contacts to facilitate hole extraction through the back interface of CIGS.
authors.affiliation: Department of Chemistry and Biochemistry, University of California San Diego , La Jolla, California 92093-0358, United States.
authors.forename: Kasra
authors.initials: K
authors.lastname: Sardashti
authors.affiliation: IBM TJ Watson Research Center , Yorktown Heights, New York 10598, United States.
authors.forename: Richard
authors.initials: R
authors.lastname: Haight
authors.affiliation: California Institute for Telecommunications and Information Technology, University of California San Diego , La Jolla, California 92093-0436, United States.
authors.forename: Ryan
authors.initials: R
authors.lastname: Anderson
authors.affiliation: National Renewable Energy Laboratory , Golden, Colorado 80401, United States.
authors.forename: Miguel
authors.initials: M
authors.lastname: Contreras
authors.affiliation: California Institute for Telecommunications and Information Technology, University of California San Diego , La Jolla, California 92093-0436, United States.
authors.forename: Bernd
authors.initials: B
authors.lastname: Fruhberger
authors.affiliation: Department of Chemistry and Biochemistry, University of California San Diego , La Jolla, California 92093-0358, United States.
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Kummel
keywords: CIGSe; Cryo-FIB; KPFM; back contacts; thin-film photovoltaics