There Is A Semiconductor Heterostructure Made Of Gaas And Algaas This Structure Takes A Cubic Shape With The Volume 1 C 1 (122.78 KiB) Viewed 67 times
There is a semiconductor heterostructure made of GaAs and AlGaAs. This structure takes a cubic shape with the volume 1 cm³. The structure has a GaAs crystal layer with the thickness 10 nm at the center, which is sandwitched by two AlGaAs layers with the thickness about 0.5 cm. The AlGaAs layer has 1-nm-thick Si doped layer at the concentration № 1.0 × 1018 cm3³ nearby the GaAs layer. Assume that the energy level in the GaAs layer is obtained by the approximation that the barrier height at the AlGaAs layer are infinitely high. The temperature is around 1 K and all doped Si are activated. The electron energy E= 0 is defined at the bottom of the conduction band of the GaAs crystal. Q8: Answer why all doped Si are activated, though the temperature is the freeze-out region of the semiconductor crystal. Q9: Calculate the number of electrons in the GaAs layer. Q10: Calculate the Fermi level position.
GaAs Lattice constant ao = 5.7 × 10-10 m Dielectric constant s = 1380 Band gap Eg= 1.4 eV Intrinsic carrier density n = 1.8 × 106 cm-³ Effective electron density №c=4.7 × 10¹7 cm-³ Effective hole density N = 7.0 × 10¹8 cm³ Effective mass of electron me* = 0.067mo Effective mass of hole m₁* = 0.40mo Binding energy of Si impurity level Ed = 0.0058 eV
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