Publication
Title
Native point defects in $CuIn_{1-x}Ga_{x}Se_{2}$ : hybrid density functional calculations predict the origin of p- and n-type conductivity
Author
Abstract
 We have performed a first-principles study of the p- and n-type conductivity in CuIn1−xGaxSe2 due to native point defects, based on the HSE06 hybrid functional. Band alignment shows that the band gap becomes larger with x due to the increasing conduction band minimum, rendering it hard to establish n-type conductivity in CuGaSe2. From the defect formation energies, we find that In/GaCu is a shallow donor, while VCu, VIn/Ga and CuIn/Ga act as shallow acceptors. Using the total charge neutrality of ionized defects and intrinsic charge carriers to determine the Fermi level, we show that under In-rich growth conditions InCu causes strongly n-type conductivity in CuInSe2. Under increasingly In-poor growth conditions, the conductivity type in CuInSe2 alters to p-type and compensation of the acceptors by InCu reduces, as also observed in photoluminescence experiments. In CuGaSe2, the native acceptors pin the Fermi level far away from the conduction band minimum, thus inhibiting n-type conductivity. On the other hand, CuGaSe2 shows strong p-type conductivity under a wide range of Ga-poor growth conditions. Maximal p-type conductivity in CuIn1−xGaxSe2 is reached under In/Ga-poor growth conditions, in agreement with charge concentration measurements on samples with In/Ga-poor stoichiometry, and is primarily due to the dominant acceptor CuIn/Ga.
Language
English
Source (journal)
Physical chemistry, chemical physics / Royal Society of Chemistry [London] - Cambridge, 1999, currens
Publication
Cambridge : 2014
ISSN
1463-9076 [print]
1463-9084 [online]
Volume/pages
16:40(2014), p. 22299-22308
ISI
000343072800042
Full text (Publisher's DOI)
Full text (open access)
UAntwerpen
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