NNSE618-L21-heterojunctions

NNSE618-L21-heterojunctions - 1 Lecture contents...

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NNSE 618 Lecture #21 1 Lecture contents Heterojunctions Types of heterostructures Electrostatics Current Isotype heterojunctions
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NNSE 618 Lecture #21 2 Determine band discontinuities D E c and E v from difference in electron affinities: Determine the built-in voltage from the difference in work functions. Draw the bands at for the appropriate doping Determine V n and V p and x n and x p from the solution of Poisson’s Equation using Full Depletion Approximation with f i as a boundary condition. Heterojunction: Band lineup Formation of P-n heterojunction 2 1 m m Fp Fn i q q E E q f
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NNSE 618 Lecture #21 3 Type I (Straddling Alignment) AlGaAs/GaAs GaSb/AlSb GaAs/GaP Type II (Staggered) InP/Al 0.48 In 0.52 P InxGa 1-x As/Ga x Sb x As Al x In 1-x As/InP Type III (broken gap) InAs/GaSb Types of heterojunctions From Shur, 2003
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NNSE 618 Lecture #21 4 -6 -5.5 -5 -4.5 -4 -3.5 -3 0 0.2 0.4 0.6 0.8 1 Al content Band Energy, eV Conduction band Valence band (-0.46x) Type III : InAs/GaSb
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NNSE 618 Lecture #21 5 Band edges alignment (From Tiwari and Frank, APL 1992)
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NNSE 618 Lecture #21 6 Junction barrier: The same using valence band parameters Or combining the two, independent of the free carrier concentrations: p-N heterojunction: electrostatics Flat-band diagram of a p-n heterojunctions cn p cp n c Fp Fn i N n N n kT E E E q 0 0 ln D
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This note was uploaded on 11/08/2011 for the course NNSE 618 taught by Professor Sergeoktyabrsky during the Spring '11 term at SUNY Albany.

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NNSE618-L21-heterojunctions - 1 Lecture contents...

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