Electron spin resonance study of transport dynamics of the self-trapped hole in calcium fluoride

Thesis/Dissertation · Mon Jan 01 00:00:00 EST 1973

DOI:https://doi.org/10.2172/4404367· OSTI ID:4404367

Fuller, Gene E. ^[1]; Moran, P. R. ^[1]

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1. Univ. of Wisconsin, Madison, WI (United States)

A study was made of the formation, annealing, and spin-lattice relaxation of self-trapped holes in CaF₂ single crystals. Production of self-trapped holes in CaF₂ subjected to 120-kVp x rays is discussed. A simple saturating exponential x-ray exposure dependence is observed with an initial production rate of approximately one self-trapped hole produced per 40 eV of absorbed photon energy and a saturated concentration of about 2 5 x 10¹⁶ holes/cm³. The production behavior observed by ESR is compared to thermoluminescent (TL) and thermally activated current (TAC) studies, showing that the production supralinearity observed in TL studies is due to the recombination mechanism rather than the production mechanism. Isothermal annealing of the self-trapped hole was carried out at 110 to 140 deg K. A two- component decay was found with each component obeying linear kinetics. A two- step coupled decay model for the two-component behavior is discussed, and correlations between the ESR isothermal annealing results and the TL and TAC studies are described. Analysis of the temperature dependence of the isothermal annealing rate shows that the selftrapped hole annealing behavior is well described by the theory of small polarons. At temperatures near 140 deg K, the decay rates behave approximately as simple thermally activated functions with activation energies of 0.325 eV for the slower decay component and 0.30 eV for the faster decay component. The spin--lattice relaxation rate of the self- trapped holes was studied from 78 to 140 deg K. A well-behaved temperature dependence was observed showing no correlation with the annealing kinetics. The relaxation rate can be fitted either to a simple thermal activation function or to a power law function of the temperature.

• Research Organization: Univ. of Wisconsin, Madison, WI (United States)
• Sponsoring Organization: US Atomic Energy Commission (AEC)
• DOE Contract Number: AT(11-1)-1105
• NSA Number: NSA-29-005563
• OSTI ID: 4404367
• Report Number(s): COO-1105-203
• Resource Relation: Other Information: Thesis. Submitted by G.E. Fuller. Orig. Receipt Date: 30-JUN-74
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
*CALCIUM FLUORIDES- PHYSICAL RADIATION EFFECTS
*HOLES- TRAPPING
ACTIVATION ENERGY
ANNEALING
DECAY
ELECTRIC CURRENTS
ELECTRON SPIN RESONANCE
KINETICS
LOW TEMPERATURE
MONOCRYSTALS
PHOTON BEAMS
POLARONS
SPIN-LATTICE RELAXATION
TEMPERATURE DEPENDENCE
THERMOLUMINESCENCE
X RADIATION