Interfacial layer formations between Cu(In,Ga)Se{sub 2} and In{sub x}S{sub y} layers

Journal Article · Thu Dec 15 00:00:00 EST 2005 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.2149166· OSTI ID:20787721

Abou-Ras, D; Kostorz, G; Strohm, A; Schock, H -W; Tiwari, A N ^[1]

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1. ETH Zuerich, Thin Film Physics Group, Laboratory for Solid State Physics, Technopark, Technoparkstrasse 1, 8005 Zuerich, Switzerland, and ETH Zuerich, Institute of Applied Physics, 8093 Zuerich (Switzerland)

Cu(In,Ga)Se{sub 2} (CIGS) thin-film solar cells with In{sub x}S{sub y} buffer layers deposited by physical vapor deposition yield efficiencies of up to 14.8%. For substrate temperatures during the In{sub x}S{sub y} deposition ranging from 23 to 200 deg. C, air annealing of the completed solar cells leads to an improvement of the photovoltaic performance. However, at substrate temperatures of 300 deg. C, the efficiencies are practically zero, and air annealing does not improve this value. To understand the effects of substrate temperature and air annealing on the CIGS/In{sub x}S{sub y} interfaces of the solar cells, these interfaces have been studied by means of bright-field and high-resolution transmission electron microscopy, selected-area electron diffraction (SAED), and energy-dispersive x-ray spectrometry (EDX). It is shown that air annealing leads to a substantial Cu depletion on the CIGS side of the CIGS/In{sub x}S{sub y} interface, probably inducing the formation of a compositionally graded interface between the buffer and CIGS. For the 300 deg. C sample, CuIn{sub 5}S{sub 8} formed instead of In{sub x}S{sub y}, as identified by means of SAED and EDX. The large density of vacancies and defects in the spinel-type cubic crystal structure of CuIn{sub 5}S{sub 8} provides a large number of recombination centers at the heterojunction of the solar cell, thus deteriorating considerably its photovoltaic performance.

• OSTI ID: 20787721
• Journal Information: Journal of Applied Physics, Vol. 98, Issue 12; Other Information: DOI: 10.1063/1.2149166; (c) 2005 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AIR
ANNEALING
COPPER SELENIDES
ELECTRON DIFFRACTION
GALLIUM COMPOUNDS
HETEROJUNCTIONS
INDIUM COMPOUNDS
INTERFACES
LAYERS
PHOTOVOLTAIC EFFECT
PHYSICAL VAPOR DEPOSITION
RECOMBINATION
SEMICONDUCTOR MATERIALS
SOLAR CELLS
SPINELS
SUBSTRATES
THIN FILMS
TRANSMISSION ELECTRON MICROSCOPY
VACANCIES
X-RAY SPECTROSCOPY