TY - GEN
T1 - Nanophase semiconductors embedded within transparent conductive oxides matrices as optical sensitizers for photovoltaic applications
AU - Allen, C. G.
AU - Shih, G. H.
AU - Beal, R. J.
AU - Potter, B. G.
PY - 2010
Y1 - 2010
N2 - The optical absorption of a transparent conductive oxide (TCO), which is often used as the basis for junction or contact layers in thin film photovoltaics, can be tailored by incorporating a nanophase semiconductor (SC) component. Using a, dual-source, sequential R.F. magnetron sputter deposition technique, we manipulate the optical and electronic properties of SC:TCO composites by varying the local and extended nanophase assembly and composition. The present study explores nanocomposite systems based on Ge:ZnO and Ge:ITO. The impact of host material (ITO vs. ZnO) on the evolution of nanostructure is investigated. Heat treatment of the as-deposited films results in an increased crystallinity of the TCO and SC components, confirmed by X-ray diffraction and Raman spectroscopy studies. The presence of the SC phase is found to influence TCO grain growth and crystallographic orientation, and modification of the SC phase distribution is coincident with the morphological development of the TCO phase in both composite systems. Upon heattreatment, the high-energy optical absorption edge of the nanocomposite is blue-shifted compared to that of the corresponding as-deposited material. This indicates the development of quantum-confinement conditions for photocarriers within the Ge phase which leads to an increased energy gap over that expected for the more bulk-like, asdeposited Ge material. Under the deposition and thermal treatment conditions used in the present study, the spectral absorption response is consistent between the ZnO and ITO-based thin films examined. This suggests that carrier confinement conditions are mediated by the development of similar Ge-phase local spatial extent and Ge:TCO interfacial structures in both systems, regardless of TCO identity.
AB - The optical absorption of a transparent conductive oxide (TCO), which is often used as the basis for junction or contact layers in thin film photovoltaics, can be tailored by incorporating a nanophase semiconductor (SC) component. Using a, dual-source, sequential R.F. magnetron sputter deposition technique, we manipulate the optical and electronic properties of SC:TCO composites by varying the local and extended nanophase assembly and composition. The present study explores nanocomposite systems based on Ge:ZnO and Ge:ITO. The impact of host material (ITO vs. ZnO) on the evolution of nanostructure is investigated. Heat treatment of the as-deposited films results in an increased crystallinity of the TCO and SC components, confirmed by X-ray diffraction and Raman spectroscopy studies. The presence of the SC phase is found to influence TCO grain growth and crystallographic orientation, and modification of the SC phase distribution is coincident with the morphological development of the TCO phase in both composite systems. Upon heattreatment, the high-energy optical absorption edge of the nanocomposite is blue-shifted compared to that of the corresponding as-deposited material. This indicates the development of quantum-confinement conditions for photocarriers within the Ge phase which leads to an increased energy gap over that expected for the more bulk-like, asdeposited Ge material. Under the deposition and thermal treatment conditions used in the present study, the spectral absorption response is consistent between the ZnO and ITO-based thin films examined. This suggests that carrier confinement conditions are mediated by the development of similar Ge-phase local spatial extent and Ge:TCO interfacial structures in both systems, regardless of TCO identity.
KW - Nanocomposite
KW - Quantum-confined semiconductor
KW - Thin-film
KW - Transparent conductive oxides
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U2 - 10.1117/12.859875
DO - 10.1117/12.859875
M3 - Conference contribution
AN - SCOPUS:77957842434
SN - 9780819482686
T3 - Proceedings of SPIE - The International Society for Optical Engineering
BT - Next Generation (Nano) Photonic and Cell Technologies for Solar Energy Conversion
T2 - Next Generation (Nano) Photonic and Cell Technologies for Solar Energy Conversion
Y2 - 1 August 2010 through 4 August 2010
ER -