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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. Update on Photocathode.
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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
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) Grown at UIUC by Ryan
AFM Image – before annealing • 2D Surface • Surface roughness : 0.141 nm
After annealing • We have some chunks on the surface after annealing samples
After annealing • We have some chunks on the surface after annealing samples • Surface roughness : rms 0.164nm
Plans in near future • EDS (Energy-dispersive X-ray spectroscopy) • Analyze chemical composition • Surface Cleaning