Strained Superlattice GaAs

1
Strained Superlattice GaAs
SVT associates, per SLAC specs.
2
Higher Quantum Efficiency

QE ()
QE 1 versus 0.2 from traditional strained
layer material
we operate here
Wavelength (nm)
3
Higher Beam polarization
Measurements at Test Cave as high as 85 Recent
injector measurement 82 Typical polarization
from traditional material 75
Polarization ()
Wavelength for Good QE and Polarization
Wavelength (nm)
4
Analyzing power (ie QE anisotropy)
Analyzing power smaller by factor of 3 compared
with strained-layer material 4 versus
12. This means Smaller inherent intensity and
position asymmetries on beam.
Analyzing power ()
Wavlength for good QE and polarization
Wavelength (nm)
5
QE vs hydrogen cleaning
Typical H-dose to clean anodized samples
Drawback Delicate material Cant clean with
atomic hydrogen Makes it tough to anodize edge
of cathode Try arsenic capped samples (on order)
QE ()
Hydrogen exposure time (min)
6
Superlattice vs strained layer

• Polarization higher than strained layer P 80
• QE is 5 times higher QE 1
• Analyzing power smaller A.P. 3
• Material difficult to clean once it gets dirty.
  
• Makes it tough to anodize edge of sample.
• Suffer shorter operating lifetime. ?

Pros
Cons