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High Electron Mobility Transistor (HEMT)

High Electron Mobility Transistor (HEMT). Flament Benjamin. PLAN. Presentation Fabrication. Presentation. 1980 at Fujitsu TEGFET, MODFET, HFET Goal->transportation in a doped material. Presentation. Heterojunction: 2 layers Highly doped layer with grand gap

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High Electron Mobility Transistor (HEMT)

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  1. High Electron Mobility Transistor (HEMT) Flament Benjamin

  2. PLAN • Presentation • Fabrication

  3. Presentation • 1980 at Fujitsu • TEGFET, MODFET, HFET • Goal->transportation in a doped material

  4. Presentation • Heterojunction: 2 layers • Highly doped layer with grand gap • Non-doped layer with small gap

  5. PLAN • Presentation • Fabrication

  6. Plan • Cleaning • Deposition, MBE • Ohmic contacts

  7. Fabrication • Cleaning of the wafer • GaAs wafer->more complicated than Si wafer • Difficulties to remove the oxide of Ga and As • We use the electron cyclotron resonance (ECR)

  8. Fabrication • As oxide is removed by heating and : x=1, 3, 5 stands for the various oxides of arsenic • Ga oxide is removed by:

  9. Fabrication • Becomes volatile at 200°C so we choose a temperature of 400°C

  10. Fabrication • We grow the different layer by molecular beam epitaxy (MBE)

  11. 30 periods of AlGaAs/GaAs superlattice buffer 30 periods of AlGaAs/GaAs superlattice buffer

  12. 120 Å of In(0.2)Ga(0.8)As

  13. 35 Å of Al(0.23)Ga(0.77)As

  14. 250 Å of Al(0.23)Ga(0.77)As

  15. Fabrication

  16. Fabrication

  17. Fabrication

  18. Fabrication

  19. Fabrication • 3 layers: • PPMA for the bottom layer • PMIPK for the middle layer • PPMA for the top layer • PPMA(polypropylmethacrylate) • PMIPK(polymethylisopropenylketone)

  20. Fabrication • Using deep UV lithography

  21. Research • Lattice matching

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