The effect of Na on the electronic properties of Cu(In,Ga)Se2 thin films: A local-probe study

D. Azulay; D. Abou-Ras; I. Popov; I. Balberg; O. Millo

doi:10.1002/pssr.201600058

The effect of Na on the electronic properties of Cu(In,Ga)Se₂ thin films: A local-probe study

D. Azulay
, D. Abou-Ras
, I. Popov
, I. Balberg
, O. Millo

Racah Institute of Physics

The Hebrew University of Jerusalem

Research output: Contribution to journal › Article › peer-review

Abstract

We investigated the effect of Na incorporation on the electronic properties of polycrystalline CuIn_0.7Ga_0.3Se₂ thin films using scanning tunneling microscopy and spectroscopy. The tunneling spectra indicate a reduced in-gap density of states at grain boundaries and reveal a downward band-bending in Na-rich grain boundaries with respect to the adjacent grains, in agreement with our conductive atomic force microscopy data. It thus appears that Na passivates deep-level defects at grain boundaries and induces a downward band-bending there. Moreover, we provide evidence that Na passivates mainly Cu vacancy related defects. We suggest that the grain-boundary passivation, which reduces the recombination rate of photogenerated carriers, is at least of major importance in the well known Na-induced improvement in the efficiency of the corresponding solar cells.

Original language	English
Pages (from-to)	448-452
Number of pages	5
Journal	Physica Status Solidi - Rapid Research Letters
Volume	10
Issue number	6
DOIs	https://doi.org/10.1002/pssr.201600058
State	Published - 1 Jun 2016

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

SDG 7 Affordable and Clean Energy

Keywords

Cu(In,Ga)Se
electronic properties
grain boundaries
scanning tunneling spectroscopy

ASJC Scopus subject areas

General Materials Science
Condensed Matter Physics

Access to Document

10.1002/pssr.201600058

Cite this

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title = "The effect of Na on the electronic properties of Cu(In,Ga)Se2 thin films: A local-probe study",

abstract = "We investigated the effect of Na incorporation on the electronic properties of polycrystalline CuIn0.7Ga0.3Se2 thin films using scanning tunneling microscopy and spectroscopy. The tunneling spectra indicate a reduced in-gap density of states at grain boundaries and reveal a downward band-bending in Na-rich grain boundaries with respect to the adjacent grains, in agreement with our conductive atomic force microscopy data. It thus appears that Na passivates deep-level defects at grain boundaries and induces a downward band-bending there. Moreover, we provide evidence that Na passivates mainly Cu vacancy related defects. We suggest that the grain-boundary passivation, which reduces the recombination rate of photogenerated carriers, is at least of major importance in the well known Na-induced improvement in the efficiency of the corresponding solar cells.",

keywords = "Cu(In,Ga)Se, electronic properties, grain boundaries, scanning tunneling spectroscopy",

author = "D. Azulay and D. Abou-Ras and I. Popov and I. Balberg and O. Millo",

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TY - JOUR

T1 - The effect of Na on the electronic properties of Cu(In,Ga)Se2 thin films

T2 - A local-probe study

AU - Azulay, D.

AU - Abou-Ras, D.

AU - Popov, I.

AU - Balberg, I.

AU - Millo, O.

PY - 2016/6/1

Y1 - 2016/6/1

N2 - We investigated the effect of Na incorporation on the electronic properties of polycrystalline CuIn0.7Ga0.3Se2 thin films using scanning tunneling microscopy and spectroscopy. The tunneling spectra indicate a reduced in-gap density of states at grain boundaries and reveal a downward band-bending in Na-rich grain boundaries with respect to the adjacent grains, in agreement with our conductive atomic force microscopy data. It thus appears that Na passivates deep-level defects at grain boundaries and induces a downward band-bending there. Moreover, we provide evidence that Na passivates mainly Cu vacancy related defects. We suggest that the grain-boundary passivation, which reduces the recombination rate of photogenerated carriers, is at least of major importance in the well known Na-induced improvement in the efficiency of the corresponding solar cells.

AB - We investigated the effect of Na incorporation on the electronic properties of polycrystalline CuIn0.7Ga0.3Se2 thin films using scanning tunneling microscopy and spectroscopy. The tunneling spectra indicate a reduced in-gap density of states at grain boundaries and reveal a downward band-bending in Na-rich grain boundaries with respect to the adjacent grains, in agreement with our conductive atomic force microscopy data. It thus appears that Na passivates deep-level defects at grain boundaries and induces a downward band-bending there. Moreover, we provide evidence that Na passivates mainly Cu vacancy related defects. We suggest that the grain-boundary passivation, which reduces the recombination rate of photogenerated carriers, is at least of major importance in the well known Na-induced improvement in the efficiency of the corresponding solar cells.

KW - Cu(In,Ga)Se

KW - electronic properties

KW - grain boundaries

KW - scanning tunneling spectroscopy

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DO - 10.1002/pssr.201600058

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