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Title: Near infrared laser annealing of CdTe and in-situ measurement of the evolution of structural and optical properties

Here, the high performance of polycrystalline CdTe thin film solar cells is enabled by annealing in the presence of Cl. This process is typically carried out for tens of minutes resulting in reduction of defect states within the bandgap among other beneficial effects. In this work, we investigate laser annealing as a means of rapidly annealing CdTe using a continuous wave sub-bandgap 1064 nm laser. The partial transmission of the beam allows us to monitor the annealing process in-situ and in real time. We find that optoelectronic and structural changes occur through two distinct kinetic processes resulting in the removal of deep defects and twinned regions, respectively. A multilayer optical model including surface roughness is used to interpret both the in-situ transmission as well as ex-situ reflectivity measurements. These experiments demonstrate beneficial material changes resulting from sub-bandgap laser-driven CdCl 2 treatment of CdTe in minutes, which is an important step towards accelerating the processing of the CdTe absorber layer.
Authors:
 [1] ;  [1] ;  [2] ;  [3] ;  [3] ;  [4] ;  [5]
  1. Univ. of Utah, Salt Lake City, UT (United States). Dept. of Materials Science and Engineering
  2. Univ. of Toledo, OH (United States). Dept. of Physics and Astronomy
  3. Stanford Univ., CA (United States). Dept. of Materials Science and Engineering
  4. Univ. of South Florida, Tampa, FL (United States). Dept. of Electrical Engineering
  5. Univ. of Utah, Salt Lake City, UT (United States). Dept. of Materials Science and Engineering and Dept. of Electrical and Computer Engineering
Publication Date:
Grant/Contract Number:
EE0004946
Type:
Accepted Manuscript
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 119; Journal Issue: 16; Journal ID: ISSN 0021-8979
Publisher:
American Institute of Physics (AIP)
Research Org:
Stanford Univ., CA (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; annealing; semiconductors; optical instruments; band gap; optical absorption; measurement theory; thin films; lasers; profilometry; optical properties
OSTI Identifier:
1470760
Alternate Identifier(s):
OSTI ID: 1249831

Simonds, Brian J., Misra, Sudhajit, Paudel, Naba, Vandewal, Koen, Salleo, Alberto, Ferekides, Christos, and Scarpulla, Michael A.. Near infrared laser annealing of CdTe and in-situ measurement of the evolution of structural and optical properties. United States: N. p., Web. doi:10.1063/1.4947186.
Simonds, Brian J., Misra, Sudhajit, Paudel, Naba, Vandewal, Koen, Salleo, Alberto, Ferekides, Christos, & Scarpulla, Michael A.. Near infrared laser annealing of CdTe and in-situ measurement of the evolution of structural and optical properties. United States. doi:10.1063/1.4947186.
Simonds, Brian J., Misra, Sudhajit, Paudel, Naba, Vandewal, Koen, Salleo, Alberto, Ferekides, Christos, and Scarpulla, Michael A.. 2016. "Near infrared laser annealing of CdTe and in-situ measurement of the evolution of structural and optical properties". United States. doi:10.1063/1.4947186. https://www.osti.gov/servlets/purl/1470760.
@article{osti_1470760,
title = {Near infrared laser annealing of CdTe and in-situ measurement of the evolution of structural and optical properties},
author = {Simonds, Brian J. and Misra, Sudhajit and Paudel, Naba and Vandewal, Koen and Salleo, Alberto and Ferekides, Christos and Scarpulla, Michael A.},
abstractNote = {Here, the high performance of polycrystalline CdTe thin film solar cells is enabled by annealing in the presence of Cl. This process is typically carried out for tens of minutes resulting in reduction of defect states within the bandgap among other beneficial effects. In this work, we investigate laser annealing as a means of rapidly annealing CdTe using a continuous wave sub-bandgap 1064 nm laser. The partial transmission of the beam allows us to monitor the annealing process in-situ and in real time. We find that optoelectronic and structural changes occur through two distinct kinetic processes resulting in the removal of deep defects and twinned regions, respectively. A multilayer optical model including surface roughness is used to interpret both the in-situ transmission as well as ex-situ reflectivity measurements. These experiments demonstrate beneficial material changes resulting from sub-bandgap laser-driven CdCl2 treatment of CdTe in minutes, which is an important step towards accelerating the processing of the CdTe absorber layer.},
doi = {10.1063/1.4947186},
journal = {Journal of Applied Physics},
number = 16,
volume = 119,
place = {United States},
year = {2016},
month = {4}
}