Properties of Reactively Sputtered Oxygenated Cadmium Sulfide (CdS:O) and Their Impact on CdTe Solar Cell Performance

Daniel M. Meysing, Colin A. Wolden, Michelle M. Griffith, Hasitha Mahabaduge, Joel Pankow, Matthew O. Reese, James M. Burst, William L. Rance, Teresa M. Barnes

Research output: Contribution to journalArticlepeer-review

66 Scopus Citations

Abstract

Oxygenated cadmium sulfide (CdS:O) is commonly used as the n-Type window layer in highperformance CdTe heterojunction solar cells. This layer is deposited by reactive sputtering, but the optimal amount of oxygen in the sputtering ambient is highly dependent on the specific system and process employed. In this work, the intrinsic properties of CdS:O were measured as a function of the oxygen content (0%-10%) in the sputtering ambient and correlated to device performance with the goal of better defining optimal CdS:O properties for CdTe solar cells. Optimal performance was found using CdS:O films that contained 40 at. % oxygen as measured by Rutherford backscattering spectrometry. X-ray photoelectron spectroscopy confirmed these results and showed that oxygen is incorporated primarily as oxygenated sulfur compounds (SOx). Device efficiency improved from 10.5% using CdS to >14% with CdS:O due largely to increases in short-circuit current density as well as a modest improvement in open-circuit voltage. The transparency of the CdS:O films was well correlated with observed improvements in blue quantum efficiency with increasing oxygen content. The optical bandgap of as-deposited CdS:O was identified as a simple metric for process optimization and transfer, with 2.8 eV being ideal for the device architecture employed. VC 2014 American Vacuum Society.

Original languageAmerican English
Article number021203
Number of pages7
JournalJournal of Vacuum Science and Technology A: Vacuum, Surfaces and Films
Volume33
Issue number2
DOIs
StatePublished - Mar 2015
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2015 AVS Science and Technology Society. All rights reserved.

NREL Publication Number

  • NREL/JA-5K00-62898

Keywords

  • bandgap
  • cadmium sulfide solar cells films
  • cadmium telluride (CdTe) photovoltaic solar cells modules
  • photovoltaics (PV)
  • sputtering
  • thin films

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