1. Surface morphology of p-GaAs
Seon W. Lee† , H. Hau Wang‡ , Klaus Attenkofer
High Energy Physics Division †, Materials Science Division ‡
X-Ray Sciences Division
Argonne National Laboratory
Tuesday, July 27, 2010
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2. Update on Photocathode
The active layer exists of 3 layers of GaAs (direct bandgap: 1.456) with different doping:
the third layer is 10nm thick with 1x10^18 Zn doping.
The thickness of the following layer is varying (0nm,50nm,100nm,200nm)
The bottom layer has a 2x10^19 Zn concentration and is 10nm thick
Buffer layer Al.75Ga.25As 1um thick layer thick layer (band gap: 2.36eV, IR refractive index 2.95).
GaAs substrate (100)
Grown by MOVPE (Molecular Vapor Phase Deposition)
Sample was grown from (100) GaAs substrate. It grown at UIUC by Ryan.
Sample is composed of buffer layer and active layer.
Buffer layer is AlGaAs 1um thick. Band gap of buffer layer is 2.36 eV , IR refractive index is 2.95.
Active layer is composed of three layer.
Grown at UIUC by Ryan
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3. AFM Image – before annealing
2D Surface
Surface roughness :
0.141 nm

4. After annealing
We have some chunks on the surface after annealing samples

5. After annealing
We have some chunks on the surface after annealing samples
Surface roughness : rms 0.164nm

6. Plans in near future EDS (Energy-dispersive X-ray spectroscopy)
Analyze chemical composition
Surface Cleaning
for the elemental analysis or chemical characterization of a sample.
EDS spectrum to analyze, analyzing X-rays emitted by the matter in response to being hit with charged particles
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