The effect of composition on the bandgap width in insulating NbxTayOz nanolayers

The bandgap width in niobium tantalate (NbxTayOz) films with Ta/(Ta+Nb) ratio of 10.7, 41.9, and 68.4 % are studied in this work. The samples were prepared by atomic layer deposition on (100)Si/TaN substrates, some of them subjected to crystallization annealing. Two photoconductivity spectral thresh...

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Bibliographic Details
Main Authors: Wang, W C, Chou, H Y, Badylevich, M, Blomberg, T, Wenger, Ch, Kittl, J A, Afanas'ev, V V
Format: Conference Proceeding
Language:English
Subjects:
Atomic layer epitaxy
Composition effects
Crystallization
Electron states
Energy gap
Niobium
Photoconductivity
Silicon substrates
Tantalum
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Summary:The bandgap width in niobium tantalate (NbxTayOz) films with Ta/(Ta+Nb) ratio of 10.7, 41.9, and 68.4 % are studied in this work. The samples were prepared by atomic layer deposition on (100)Si/TaN substrates, some of them subjected to crystallization annealing. Two photoconductivity spectral thresholds are found in all the studied samples: one at around 4.2 eV and another in range 3.2–3.8 eV, which may be correlated with the bandgaps associated with TaOx and NbOx sub-networks, respectively. The observed preservation of the narrowest bandgap of NbOx despite the addition of the Ta cation indicates that electron states of Nb and Ta have insufficient mutual interaction to affect the gap width of two oxide sub-networks.
ISSN:1757-8981
1757-899X
DOI:10.1088/1757-899X/41/1/012004