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02-June-2003

02-June-2003. Aseem Talukdar Department of Physics University of Cincinnati Cincinnati-OH. Fabrication of 2D electron System by MBE and QHE. 2 D electron System MBE technique QHE. Outlines:. E n =(n+1/2) ħ w c + g m B B + e z w c =eB/ m*

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02-June-2003

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  1. 02-June-2003 Aseem Talukdar Department of Physics University of Cincinnati Cincinnati-OH Fabrication of 2D electron System by MBE and QHE

  2. 2 D electron System MBE technique QHE Outlines:

  3. En=(n+1/2) ħwc+ gmBB+ez wc=eB/m* nk(r)~n(y+cpx/eB) ei(kxx+kzz) 2D electron System Density of States ::

  4. e~ p2 ħ2/(2md2) for 2D behavior kBT<De d ~ 10 nm T~130 K E~100 meV d~ 2 nm Potential well of width d

  5. MOS structure (MOSFET) GaAs/Ga1-xAlxAs heterostructure Examples::

  6. Technique for growing semiconductor layered structure Allows Controlled growth of semiconductor layers with monolayer precision. Molecular Beam Epitaxy::

  7. Schematic of MBE Effusion Cells CAR assembly Cryopanels RHEED Gun MBE::

  8. Lorentz Force Law :: Rh=Ey/(Jx B)=Vy d/(BIx) Rh – Hall Coefficient d - thickness (along Z-axis) Drude Picture :: Rh=-1/(ne) =>Hall Resistance Rxy=-Ey/Jx=RhB a B Classical Hall Effect(1879)

  9. QHE-Klaus von Klitzing (1980) Transverse resistance a B

  10. Conclusions:: • MBE provides a convenient way to prepare 2D electron system • Ability to control band gap and grow one layer of semiconductor material at a time results in the possibility of development of electronic and optoelectronic devices

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