282588 Energy Levels, Electronic Properties, and Rectification in Ultrathin P-NiO Films Synthesized by Atomic Layer Deposition

Thursday, November 1, 2012: 5:22 PM
Fayette (Westin )
Elijah Thimsen, Material Science Division, Argonne National Laboratory, Argonne , IL, Alex Martinson, Material Science Division, Argonne National Laboratory, Argonne, IL, Jeffrey Elam, Energy Systems Division, Argonne National Laboratory, Argonne, IL and Michael J. Pellin, Physical Sciences and Engineering Directorate, Argonne National Laboratory, Argonne, IL

NiO is an attractive p-type transparent semiconductor that is being explored for a variety of applications.  We report a systematic study of the electronic properties, relevant to hole-transporting materials in solar energy conversion applications, of NiO synthesized by atomic layer deposition (ALD).  The accepter concentration, flat band potential, and valence band position were determined by electrochemical Mott-Schottky analysis of impedance data in aqueous electrolytes for films less than 100 nm in thickness on F:SnO2 (FTO) coated glass substrates.  The effects of post-deposition annealing and film thickness were studied. Oxidation of the NiO was observed at temperatures as low as 300 oC in 1 atmosphere of oxygen.  Films annealed at 400 oC and above in Ar exhibited signs of thermal decomposition.  Thinner films were found to have a higher carrier concentration.  F:SnO2 and thermally-evaporated Ag were both observed to form ohmic contact to ALD-synthesized TiO2 and NiO.  A p/n heterojunction diode was fabricated from the transparent ALD TiO2 and NiO layers with the structure FTO/NiO/TiO2/Ag that showed rectification.

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See more of this Session: Gas Phase Deposition and Interfacial Phenomena
See more of this Group/Topical: Materials Engineering and Sciences Division