Thermal ionization induced metal-semiconductor transition and room temperature ferromagnetism in trivalent doped ZnO codoped with lithium

Journal Article · Fri Mar 07 00:00:00 EST 2014 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4867036· OSTI ID:22277948

Sivagamasundari, A.; Chandrasekar, S.; Pugaze, R.; Rajagopan, S. ^[1]

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1. Department of Chemistry, Pondicherry Engineering College, Puducherry 605 014 (India)

Thermal ionization induced metallic to semiconductor (MST) transition occurring at 460 K for Zn{sub 0.97}Al{sub 0.03}O, 463 K for Zn{sub 0.94}Al{sub 0.03}Li{sub 0.03}O, and 503 K for Zn{sub 0.91}Al{sub 0.03}Li{sub 0.03}Mn{sub 0.03}O has been found in the sol-gel synthesized (using hexamethylenetetramine), trivalent doped (Al, Mn) ZnO codoped with lithium. Increase in the thermally ionized carrier concentration due to Al doping is responsible for near band edge (NBE) peak shift causing Fermi level to move into conduction band making it metallic consistent with resistivity results. Free carrier (thermally activated) neutralization with ionized donor is responsible for semiconducting nature, which is supported from the free carrier screening produced energy shift in the NBE of photoluminescence peak. Furthermore, independently band gap shrinkage is also obtained from UV-Visible studies confirming localization induced MST. An anti-correlation is found between defect density (DLE) and room temperature ferromagnetism (RTFM) indicating intrinsic defects are not directly responsible for RTFM.

• OSTI ID: 22277948
• Journal Information: Journal of Applied Physics, Vol. 115, Issue 9; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALUMINIUM COMPOUNDS
CONCENTRATION RATIO
CORRELATIONS
FERMI LEVEL
FERROMAGNETISM
LITHIUM
LITHIUM COMPOUNDS
MANGANESE COMPOUNDS
PHASE TRANSFORMATIONS
PHOTOLUMINESCENCE
SEMICONDUCTOR MATERIALS
SOL-GEL PROCESS
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0273-0400 K
UROTROPIN
ZINC OXIDES