Large and persistent photoconductivity due to hole-hole correlation in CdS
Name
PhysRevMaterials.2.084602.pdf
Size
1.53 MB
Format
Adobe PDF
Checksum (MD5)
d2f0105694bafaf043e4fc36c471e4bd
Author(s)
Yin, Han
Akey, Austin J
Jaramillo, Rafael
Date Issued
August 2018
Journal
Physical Review Materials
Publisher
American Physical Society
Citation
Yin, Han et al. "Large and persistent photoconductivity due to hole-hole correlation in CdS." Physical Review Materials 2, 8 (August 2018): 084602 © 2018 American Physical Society
Version
Final published version
Abstract
Large and persistent photoconductivity (LPPC) in semiconductors is due to the trapping of photogenerated minority carriers at crystal defects. Theory has suggested that anion vacancies in II-VI semiconductors are responsible for LPPC due to negative-U behavior, whereby two minority carriers become kinetically trapped by lattice relaxation following photoexcitation. By performing a detailed analysis of photoconductivity in CdS, we provide experimental support for this negative-U model of LPPC. We also show that LPPC is correlated with sulfur deficiency. We use this understanding to vary the photoconductivity of CdS films over nine orders of magnitude, and vary the LPPC characteristic decay time from seconds to 10⁴s by controlling the activities of Cd²⁺ and S²⁻ ions during chemical bath deposition. We suggest a screening method to identify other materials with long-lived, nonequilibrium, photoexcited states based on the results of ground-state calculations of atomic rearrangements following defect redox reactions, with a conceptual connection to polaron formation.
MIT Department
Massachusetts Institute of Technology. Department of Materials Science and Engineering
Massachusetts Institute of Technology. Department of Mechanical Engineering
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DOI of Published Version
https://doi.org/10.1103/PhysRevMaterials.2.084602
