Characterization of vacancy defects in Cu(In,Ga)Se2 by positron annihilation spectroscopy

M. R. M. Elsharkawy; G. S. Kanda; M. V. Yakushev; E. E. Abdel-Hady; D. J.  Keeble

doi:10.1063/1.4972251

Characterization of vacancy defects in Cu(In,Ga)Se2 by positron annihilation spectroscopy

M. R. M. Elsharkawy, G. S. Kanda, M. V. Yakushev, E. E. Abdel-Hady, D. J. Keeble (Lead / Corresponding author)

Physics

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Abstract

The photovoltaic performance of Cu(In1-x,Gax)Se2 (CIGS) materials is commonly assumed to be degraded by the presence of vacancy-related defects. However, experimental identification of specific vacancy defects remains challenging. In this work we report positron lifetime measurements on CIGS crystals with x = 0, and x = 0.05, saturation trapping to two dominant vacancy defect types, in both types of crystal, is observed and found to be independent of temperature between 15–300 K. Atomic superposition method calculations of the positron lifetimes for a range of vacancy defects in CIS and CGS are reported. The calculated lifetimes support the assignment of the first experimental lifetime component to monovacancy or divacancy defects, and the second to trivacancies, or possibly the large In-Se divacancy. Further, the calculated positron parameters obtained here provide evidence that positron annihilation spectroscopy has the capability to identify specific vacancyrelated defects in the Cu(In1-x,Gax)Se2 chalcogenides.

Original language	English
Article number	125031
Number of pages	8
Journal	AIP Advances
Volume	6
Issue number	12
DOIs	https://doi.org/10.1063/1.4972251
Publication status	Published - 16 Dec 2016

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© 2016 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
Final published version, 1.47 MBLicence: CC BY

Keeble, David
- Physics - Professor (Teaching and Research) of Condensed Matter and Materials
Person: Academic

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@article{29b420ff921a482a93d91d92e161cf6a,

title = "Characterization of vacancy defects in Cu(In,Ga)Se2 by positron annihilation spectroscopy",

abstract = "The photovoltaic performance of Cu(In1-x,Gax)Se2 (CIGS) materials is commonly assumed to be degraded by the presence of vacancy-related defects. However, experimental identification of specific vacancy defects remains challenging. In this work we report positron lifetime measurements on CIGS crystals with x = 0, and x = 0.05, saturation trapping to two dominant vacancy defect types, in both types of crystal, is observed and found to be independent of temperature between 15–300 K. Atomic superposition method calculations of the positron lifetimes for a range of vacancy defects in CIS and CGS are reported. The calculated lifetimes support the assignment of the first experimental lifetime component to monovacancy or divacancy defects, and the second to trivacancies, or possibly the large In-Se divacancy. Further, the calculated positron parameters obtained here provide evidence that positron annihilation spectroscopy has the capability to identify specific vacancyrelated defects in the Cu(In1-x,Gax)Se2 chalcogenides.",

author = "Elsharkawy, {M. R. M.} and Kanda, {G. S.} and Yakushev, {M. V.} and Abdel-Hady, {E. E.} and Keeble, {D. J.}",

note = "The manuscript is part of the PhD work of Gurmeet Kanda and acknowledges EPSRC EP/J500392/1. ",

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T1 - Characterization of vacancy defects in Cu(In,Ga)Se2 by positron annihilation spectroscopy

AU - Elsharkawy, M. R. M.

AU - Kanda, G. S.

AU - Yakushev, M. V.

AU - Abdel-Hady, E. E.

AU - Keeble, D. J.

N1 - The manuscript is part of the PhD work of Gurmeet Kanda and acknowledges EPSRC EP/J500392/1.

PY - 2016/12/16

Y1 - 2016/12/16

N2 - The photovoltaic performance of Cu(In1-x,Gax)Se2 (CIGS) materials is commonly assumed to be degraded by the presence of vacancy-related defects. However, experimental identification of specific vacancy defects remains challenging. In this work we report positron lifetime measurements on CIGS crystals with x = 0, and x = 0.05, saturation trapping to two dominant vacancy defect types, in both types of crystal, is observed and found to be independent of temperature between 15–300 K. Atomic superposition method calculations of the positron lifetimes for a range of vacancy defects in CIS and CGS are reported. The calculated lifetimes support the assignment of the first experimental lifetime component to monovacancy or divacancy defects, and the second to trivacancies, or possibly the large In-Se divacancy. Further, the calculated positron parameters obtained here provide evidence that positron annihilation spectroscopy has the capability to identify specific vacancyrelated defects in the Cu(In1-x,Gax)Se2 chalcogenides.

AB - The photovoltaic performance of Cu(In1-x,Gax)Se2 (CIGS) materials is commonly assumed to be degraded by the presence of vacancy-related defects. However, experimental identification of specific vacancy defects remains challenging. In this work we report positron lifetime measurements on CIGS crystals with x = 0, and x = 0.05, saturation trapping to two dominant vacancy defect types, in both types of crystal, is observed and found to be independent of temperature between 15–300 K. Atomic superposition method calculations of the positron lifetimes for a range of vacancy defects in CIS and CGS are reported. The calculated lifetimes support the assignment of the first experimental lifetime component to monovacancy or divacancy defects, and the second to trivacancies, or possibly the large In-Se divacancy. Further, the calculated positron parameters obtained here provide evidence that positron annihilation spectroscopy has the capability to identify specific vacancyrelated defects in the Cu(In1-x,Gax)Se2 chalcogenides.

U2 - 10.1063/1.4972251

DO - 10.1063/1.4972251

M3 - Article

SN - 2158-3226

VL - 6

JO - AIP Advances

JF - AIP Advances

IS - 12

M1 - 125031

ER -

Characterization of vacancy defects in Cu(In,Ga)Se2 by positron annihilation spectroscopy

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