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Title: Direct observation of electrical properties of grain boundaries in sputter-deposited CdTe using scan-probe microwave reflectivity based capacitance measurements

Here, polycrystalline CdTe in 12% efficient solar cells has been studied using scanning microwave impedance microscopy (sMIM). The CdS/CdTe junctions were grown on transparent-conducting-oxide-coated soda lime glass using rf sputter deposition. sMIM based capacitance measurements were performed on the exposed surface of CdCl 2 treated CdTe adjacent to thermal-evaporation-deposited Cu/Au back contacts. The sMIM instrument was operated at ~3 GHz, and capacitance measurements were performed as a function of ac and dc voltage biases applied to the tip, with and without sample illumination. Although dc capacitance measurements are affected by sample topography, the differential capacitance measurement was shown to be topography independent. It was found that the grain boundaries exhibit a depleted carrier concentration as compared to the grain bulk. This depletion effect is enhanced under photo-generated carrier separation or under sufficiently large probe tip biases opposite to the majority carrier charge.
Authors:
 [1] ; ORCiD logo [2] ;  [3] ;  [2] ;  [1]
  1. Univ. of Illinois at Urbana-Champaign, IL (United States). Dept. of Materials Science and Engineering
  2. Univ. of Toledo, OH (United States). Dept. of Physics and Astronomy
  3. Univ. of Illinois at Urbana-Champaign, IL (United States). Frederick Seitz Materials Research Lab.
Publication Date:
Grant/Contract Number:
EE0005405
Type:
Accepted Manuscript
Journal Name:
Applied Physics Letters
Additional Journal Information:
Journal Volume: 107; Journal Issue: 14; Journal ID: ISSN 0003-6951
Publisher:
American Institute of Physics (AIP)
Research Org:
Univ. of Illinois at Urbana-Champaign, IL (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
Contributing Orgs:
NSG-Pilkington, Rossford, OH (United States)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 14 SOLAR ENERGY; electric measurements; oxides; semiconductors; polycrystalline material; sputter deposition; glass; electric power; transition metal chalcogenides; crystallographic defects; electrical properties and parameters
OSTI Identifier:
1469477
Alternate Identifier(s):
OSTI ID: 1223156

Tuteja, Mohit, Koirala, Prakash, MacLaren, Scott, Collins, Robert, and Rockett, Angus. Direct observation of electrical properties of grain boundaries in sputter-deposited CdTe using scan-probe microwave reflectivity based capacitance measurements. United States: N. p., Web. doi:10.1063/1.4932952.
Tuteja, Mohit, Koirala, Prakash, MacLaren, Scott, Collins, Robert, & Rockett, Angus. Direct observation of electrical properties of grain boundaries in sputter-deposited CdTe using scan-probe microwave reflectivity based capacitance measurements. United States. doi:10.1063/1.4932952.
Tuteja, Mohit, Koirala, Prakash, MacLaren, Scott, Collins, Robert, and Rockett, Angus. 2015. "Direct observation of electrical properties of grain boundaries in sputter-deposited CdTe using scan-probe microwave reflectivity based capacitance measurements". United States. doi:10.1063/1.4932952. https://www.osti.gov/servlets/purl/1469477.
@article{osti_1469477,
title = {Direct observation of electrical properties of grain boundaries in sputter-deposited CdTe using scan-probe microwave reflectivity based capacitance measurements},
author = {Tuteja, Mohit and Koirala, Prakash and MacLaren, Scott and Collins, Robert and Rockett, Angus},
abstractNote = {Here, polycrystalline CdTe in 12% efficient solar cells has been studied using scanning microwave impedance microscopy (sMIM). The CdS/CdTe junctions were grown on transparent-conducting-oxide-coated soda lime glass using rf sputter deposition. sMIM based capacitance measurements were performed on the exposed surface of CdCl2 treated CdTe adjacent to thermal-evaporation-deposited Cu/Au back contacts. The sMIM instrument was operated at ~3 GHz, and capacitance measurements were performed as a function of ac and dc voltage biases applied to the tip, with and without sample illumination. Although dc capacitance measurements are affected by sample topography, the differential capacitance measurement was shown to be topography independent. It was found that the grain boundaries exhibit a depleted carrier concentration as compared to the grain bulk. This depletion effect is enhanced under photo-generated carrier separation or under sufficiently large probe tip biases opposite to the majority carrier charge.},
doi = {10.1063/1.4932952},
journal = {Applied Physics Letters},
number = 14,
volume = 107,
place = {United States},
year = {2015},
month = {10}
}