Development of high sensitivity, high resolution ESR and its applications for studying solar cells. Ekaterina Dikarov ( Suhovoy ). m s =+1/2 . Energy . m s =-1/2 . B field . What is ESR?. ESR- Electron Spin Resonance. MW induces transition between two energy levels .
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Ekaterina Dikarov (Suhovoy )
What is ESR?
ESR- Electron Spin Resonance
MW induces transition
between two energy levels.
Spin & Magnetic Field interaction.
2D image with 3µm resolution
Spin sensitivity : ~ 108-109 spins.
Imaging resolution : Limited to ~ 20-30 μm
requirements and challenges
Dangling bonds defects
Less than 1015 spins/cm3
Thin layers ~1μm
Short relaxation times
Microwave reference source
Pulsed microwave bridge
Gradient coils drivers
Gradient coils’ structure
Resonator and sample holder
High permittivity dielectric resonators
2.2 mm @ 17 GHz
1.2 mm @ 35 GHz
Conventional ESR resonator
Dielectric resonator (first generation)
Relatively high Q ~ 1000
17 GHz – 107 spins in 1 h at RT
Microwave dielectric resonator (TiO2)
35 GHz – 106 spins in 1 h at RT
~14 GHz – 104 spins in 1 h at 5K
Twig, Y., Suhovoy, E., and Blank, A., Review of Scientific Instruments81 (2010) 104703
Twig, Y., Suhovoy, E., Hutchison, W. D., and Blank, A., Review of Scientific Instruments, 82 (2011) 076105.
Twig Y., Dikarov E., and Blank A., Journal of Magnetic Resonance, 218 (2012) 22-29.
Conventional ESR resonator (10K):
Surface resonator (10K):
2D ESR image for 10 µm thick layer of phosphorous doped 28Si, taken at 10K.