development of high sensitivity high resolution esr and its applications for studying solar cells n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Ekaterina Dikarov ( Suhovoy ) PowerPoint Presentation
Download Presentation
Ekaterina Dikarov ( Suhovoy )

Loading in 2 Seconds...

play fullscreen
1 / 13

Ekaterina Dikarov ( Suhovoy ) - PowerPoint PPT Presentation


  • 148 Views
  • Uploaded on

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 .

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Ekaterina Dikarov ( Suhovoy )' - tom


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
development of high sensitivity high resolution esr and its applications for studying solar cells

Development of high sensitivity, high resolution ESR and its applications for studying solar cells

Ekaterina Dikarov (Suhovoy )

slide2

ms=+1/2

Energy

ms=-1/2

B field

What is ESR?

ESR- Electron Spin Resonance

MW induces transition

between two energy levels.

Spin & Magnetic Field interaction.

Paramagnetic centers

slide3

100 µm

ESR Imaging

E1

E2

B0

100 µm

Optical image

B0

Frequency

2D image with 3µm resolution

slide4

The sensitivity and resolution challenge

  • Signal-to-noise-ratio (SNR) (Pulsed induction detection ESR) :

Magnetization

Sample volume

MW frequency

Quality factor

Detection bandwidth

Resonator volume

Temperature

Conventional ESR:

Spin sensitivity : ~ 108-109 spins.

Imaging resolution : Limited to ~ 20-30 μm

slide5

ESR and solar cells:

requirements and challenges

Dangling bonds defects

Less than 1015 spins/cm3

Thin layers ~1μm

Impurities

Dopants

Heterogeneous samples

Background signals

Short relaxation times

  • What is needed:
  • Increased sensitivity :1-104 electron spins.
  • Improved image resolution: 10-1000 nm.
pulsed esr imaging system
Pulsed ESR imaging system

Microwave reference source

Pulsed microwave bridge

Gradient coils drivers

Cryogenic probe

Electromagnet

Gradient coils’ structure

Temperature controller

Cryogenics

Resonator and sample holder

Control PC

dielectric resonator minimization
Dielectric resonator - minimization

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

going down further in size new surface resonators
Going down further in size – New surface resonators

~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.

poly crystalline silicon thin layers pv
Poly-crystalline silicon thin layers (PV)

Sample

  • 1.2 μm thin layer.
  • Grain size ~ 0.1μm.
  • Defect density = 9x1017cm-3
  • ~ 107 defects in measured volume. (in the surface resonator).

Surface resonator

Conventional ESR resonator (10K):

Surface resonator (10K):

imaging results
Imaging results

2D ESR image for 10 µm thick layer of phosphorous doped 28Si, taken at 10K.

slide11

Future plans

  • Smaller resonators.
  • Superconducting surface resonators.
  • Higher frequencies.
slide12

Magnetic Resonance Group members:

  • Prof. AharonBlank
  • Dr. Ygal Twig
  • Dr. Lazar Shtirberg
  • AlonPlattner
  • Michael Levit
  • Alex katchlis
  • KseniaSirota
  • OmriArbiv
  • GubrailShakkour
  • RamiMaymon
  • MadaHashem
  • Itai Katz
  • Helen Wolfson