Mid-Gap Electronic States in Zn1 xMnxO

Journal Article · Thu Sep 02 04:00:00 EDT 2010 · Physical Review. B. Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PhysRevB.82.115202· OSTI ID:990122

Johnson, Claire A.; Kittilstved, Kevin R.; Kaspar, Tiffany C.; Droubay, Timothy C.; Chambers, Scott A.; Salley, G. Mackay; Gamelin, Daniel R.

Electronic absorption, magnetic circular dichroism, photoconductivity, and valence-band X-ray photoelectron (XPS) spectroscopic measurements were performed on epitaxial Zn1 xMnxO films to investigate the origin of the new mid-gap band that appears upon introduction of Mn2+ into the ZnO lattice. Absorption and MCD spectroscopies reveal Mn2+-related intensity at energies below the first excitonic transition of ZnO, tailing well into the visible energy region, with an onset at ~2.2 eV. Photoconductivity measurements show that excitation into this visible band generates mobile charge carriers, consistent with assignment as a Mn2+/3+ photoionization transition. XPS measurements reveal the presence of occupied Mn2+ levels just above the valence-band edge, supporting this assignment. Magnetic circular dichroism measurements additionally show a change in sign and large increase in magnitude of the excitonic Zeeman splitting in Zn1 xMnxO relative to ZnO, suggesting that sp-d exchange in Zn1 xMnxO is not as qualitatively different from those in other II-VI diluted magnetic semiconductors as has been suggested. The singular electronic structure feature of Zn1 xMnxO is its Mn2+/3+ ionization level within the gap, and the influence of this level on other physical properties of Zn1 xMnxO is discussed.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 990122
• Report Number(s): PNNL-SA-73651; 19394; KP1704020
• Journal Information: Physical Review. B. Condensed Matter and Materials Physics, Journal Name: Physical Review. B. Condensed Matter and Materials Physics Journal Issue: 11 Vol. 82; ISSN 1098-0121
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ABSORPTION
CHARGE CARRIERS
ELECTRONIC STRUCTURE
EXCITATION
Environmental Molecular Sciences Laboratory
IONIZATION
MAGNETIC CIRCULAR DICHROISM
MAGNETIC SEMICONDUCTORS
ORIGIN
PHOTOCONDUCTIVITY
PHOTOIONIZATION
PHYSICAL PROPERTIES
TAILINGS
X-RAY PHOTOELECTRON SPECTROSCOPY