title: Designing metal hemispheres on silicon ultrathin film solar cells for plasmonic light trapping.
abstract: We systematically investigate the design of two-dimensional silver (Ag) hemisphere arrays on crystalline silicon (c-Si) ultrathin film solar cells for plasmonic light trapping. The absorption in ultrathin films is governed by the excitation of Fabry-Perot TEMm modes. We demonstrate that metal hemispheres can enhance absorption in the films by (1) coupling light to c-Si film waveguide modes and (2) exciting localized surface plasmon resonances (LSPRs). We show that hemisphere arrays allow light to couple to fundamental TEm and TMm waveguide modes in c-Si film as well as higher-order versions of these modes. The near-field light concentration of LSPRs also may increase absorption in the c-Si film, though these resonances are associated with significant parasitic absorption in the metal. We illustrate how Ag plasmonic hemispheres may be utilized for light trapping with 22% enhancement in short-circuit current density compared with that of a bare 100 nm thick c-Si ultrathin film solar cell.
authors.forename: Tongchuan
authors.initials: T
authors.lastname: Gao
authors.forename: Erica
authors.initials: E
authors.lastname: Stevens
authors.forename: Jung-kun
authors.initials: JK
authors.lastname: Lee
authors.forename: Paul W
authors.initials: PW
authors.lastname: Leu