Sub-band-gap photoconductivity in Co2+-doped ZnO

被引：30
|
作者：
Johnson, Claire A. [1 ]
Kaspar, Tiffany C. [2 ]
Chambers, Scott A. [2 ]
Salley, G. Mackay [1 ,3 ]
Gamelin, Daniel R. [1 ]
机构：
[1] Univ Washington, Dept Chem, Seattle, WA 98195 USA
[2] Pacific NW Natl Lab, Richland, WA 99352 USA
[3] Wofford Coll, Dept Phys, Spartanburg, SC 29303 USA
来源：
PHYSICAL REVIEW B | 2010年 / 81卷 / 12期
基金：
美国国家科学基金会;
关键词：
DILUTED MAGNETIC SEMICONDUCTORS; OPTICAL-ABSORPTION; QUANTUM DOTS; NANOCRYSTALS; SPECTROSCOPY; CRYSTALS; ELECTRODES; SPECTRA; CO2+;
D O I：
10.1103/PhysRevB.81.125206
中图分类号：
T [工业技术];
学科分类号：
08 ;
摘要：
Variable-temperature and polarized scanning photoconductivity measurements on Zn1-xCoxO epitaxial films allow description of sub-band-gap Co2+-derived photoionization excited states in this archetypal diluted magnetic oxide. Low-temperature (27 K) measurements demonstrate spontaneous ionization from the photogenerated T-4(1)(P) d-d excited state, despite the highly localized nature of this excitation. Ionization involves relaxation from this d-d state to the lower Co2+/3+ donor-type photoionization level. Variable-temperature photoconductivity measurements reveal an additional thermally assisted ionization process that enhances the d-d photoconductivity at higher temperatures. The energy barrier to thermal ionization from the T-4(1)(P) excited state at low temperatures is estimated to be E-a approximate to 43 meV.
引用
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页数：5
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