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Title: Investigation of the diffusion behavior of sodium in Cu(In,Ga)Se{sub 2} layers

Sodium diffusion in Cu(In,Ga)Se{sub 2} (CIGS) layers was investigated over a temperature range from 157 °C to 400 °C. The diffusion profiles were measured by secondary ion mass spectrometry. Sodium ions diffused from a sodium fluoride (NaF) layer on the CIGS surface into the CIGS layer. From Na diffusion profiles, the diffusion along grain boundaries could be distinguished from the diffusion into the grain interior. Atom-probe tomography measurements reveal that even at a low temperature of 157 °C bulk diffusion of sodium into CIGS occurs. Based on this data, the slower diffusion coefficient in the volume can be described by the Arrhenius equation D{sub Na}{sup V} = 9.7 × 10{sup −9} exp(−0.36 eV/k{sub B}T) cm{sup 2} s{sup −1} and the fast diffusion along the grain boundaries by D{sub Na}{sup GB} = 6.5 × 10{sup −9} exp(−0.21 eV/k{sub B}T) cm{sup 2} s{sup −1}. Hence, we propose that sodium ions do not only passivate grain boundaries, but also act as dopants in the CIGS bulk.
Authors:
; ;  [1] ; ; ;  [2]
  1. Zentrum für Sonnenenergie- und Wasserstoff-Forschung Baden Württemberg, Industriestraße 6, 70565 Stuttgart (Germany)
  2. Max-Planck-Institut für Eisenforschung, Max-Planck-Str. 1, 40237 Düsseldorf (Germany)
Publication Date:
OSTI Identifier:
22273584
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 15; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ARRHENIUS EQUATION; COPPER SELENIDES; DIFFUSION; DOPED MATERIALS; GALLIUM SELENIDES; GRAIN BOUNDARIES; INDIUM SELENIDES; LAYERS; MASS SPECTROSCOPY; SODIUM; SODIUM FLUORIDES; SODIUM IONS; SURFACES; TEMPERATURE DEPENDENCE; TOMOGRAPHY