TY - JOUR
T1 - Na-induced variations in the structural, optical, and electrical properties of Cu (In,Ga) Se2 thin films
AU - Ishizuka, Shogo
AU - Yamada, Akimasa
AU - Islam, Muhammad Monirul
AU - Shibata, Hajime
AU - Fons, Paul
AU - Sakurai, Takeaki
AU - Akimoto, Katsuhiro
AU - Niki, Shigeru
N1 - Funding Information:
This work was supported in part by the Inc. Administrative Agency, New Energy, and Industrial Technology Development Organization (NEDO) under the Ministry of Economy, Trade and Industry (METI).
PY - 2009
Y1 - 2009
N2 - The systematic variations in the structural, optical, and electrical properties of polycrystalline Cu (In,Ga) Se2 (CIGS) thin films with Na doping level were investigated. Precise control of the Na concentration in CIGS films was demonstrated using alkali-silicate glass thin layers of various thicknesses deposited on substrates prior to CIGS growth. The CIGS grain size was observed to decrease with increasing Na concentration, although the surface morphology became smoother and exhibited a stronger (112) texture, which has been demonstrated consequence of larger grain size. The Ga composition gradient in the CIGS films was found to become large due to the presence of Na during growth, which in turn led to a decrease in the nominal band gap energy. Variations in the photoluminescence spectra and electrical properties suggested that the formation of an acceptor energy state, which may originate from O Se point defects, was enhanced in the presence of Na. This result suggests that not only Na, but also the presence of O in combination with Na contributes to the compensation of point defects and enhances p -type conductivity in CIGS films.
AB - The systematic variations in the structural, optical, and electrical properties of polycrystalline Cu (In,Ga) Se2 (CIGS) thin films with Na doping level were investigated. Precise control of the Na concentration in CIGS films was demonstrated using alkali-silicate glass thin layers of various thicknesses deposited on substrates prior to CIGS growth. The CIGS grain size was observed to decrease with increasing Na concentration, although the surface morphology became smoother and exhibited a stronger (112) texture, which has been demonstrated consequence of larger grain size. The Ga composition gradient in the CIGS films was found to become large due to the presence of Na during growth, which in turn led to a decrease in the nominal band gap energy. Variations in the photoluminescence spectra and electrical properties suggested that the formation of an acceptor energy state, which may originate from O Se point defects, was enhanced in the presence of Na. This result suggests that not only Na, but also the presence of O in combination with Na contributes to the compensation of point defects and enhances p -type conductivity in CIGS films.
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U2 - 10.1063/1.3190528
DO - 10.1063/1.3190528
M3 - Article
AN - SCOPUS:69149102525
SN - 0021-8979
VL - 106
JO - Journal of Applied Physics
JF - Journal of Applied Physics
IS - 3
M1 - 034908
ER -