Structure and composition of Zn xCd 1-xS films synthesized through chemical bath deposition

B. Selin Tosun, Chelsea Pettit, Stephen A. Campbell, Eray S. Aydil

Research output: Contribution to journalArticle

Abstract

Zinc cadmium sulfide (Zn xCd 1-xS) thin films grown through chemical bath deposition are used in chalcopyrite solar cells as the buffer layer between the n-type zinc oxide and the p-type light absorbing chalcopyrite film. To optimize energetic band alignment and optical absorption, advanced solar cell architectures require the ability to manipulate x as a function of distance from the absorber-ZnCdS interface. Herein, we investigate the fundamental factors that govern the evolution of the composition as a function of depth in the film. By changing the initial concentrations of Zn and Cd salts in the bath, the entire range of overall compositions ranging from primarily cubic ZnS to primarily hexagonal CdS could be deposited. However, films are inhomogeneous and x varies significantly as function of distance from the film-substrate interface. Films with high overall Zn concentration (x > 0.5) exhibit a Cd-rich layer near the film-substrate interface because Cd is more reactive than Zn. This layer is typically beneath a nearly pure ZnS film that forms after the Cd-rich layers are deposited and Cd is depleted in the bath. In films with high overall Cd concentration (x < 0.5) the Zn concentration rises towards the films surface. Fortunately, these gradients are favorable for solar cells based on low band gap chalcopyrite films.

Original languageEnglish (US)
Pages (from-to)3676-3684
Number of pages9
JournalACS Applied Materials and Interfaces
Volume4
Issue number7
DOIs
StatePublished - Jul 25 2012

Keywords

  • cadmium sulfide
  • copper indium gallium diselenide
  • photovoltaics
  • solar cell
  • zinc sulfide

ASJC Scopus subject areas

  • Materials Science(all)

Fingerprint Dive into the research topics of 'Structure and composition of Zn <sub>x</sub>Cd <sub>1-x</sub>S films synthesized through chemical bath deposition'. Together they form a unique fingerprint.

  • Cite this