PVMD Ren van Swaaij Delft University of Technology Metal and - - PowerPoint PPT Presentation

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PVMD Ren van Swaaij Delft University of Technology Metal and - - PowerPoint PPT Presentation

Aug 19, 2023 92 likes •549 views

Metal-semiconductor junctions PVMD Ren van Swaaij Delft University of Technology Metal and semiconductor band diagram E vac E vac q sem q m E F E F Metal and semiconductor band diagram E vac E vac q sem q sem q m E F E F

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SLIDE 1

PVMD

Delft University of Technology

Metal-semiconductor junctions

René van Swaaij

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SLIDE 2

Metal and semiconductor band diagram

Evac EF qφsem EF qφm Evac

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SLIDE 3

Metal and semiconductor band diagram

Evac EF qφsem qχsem EF qφm Evac

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SLIDE 4

Learning objectives

  • Make the junction between the metal and

semiconductor

  • Schottky barrier junction
  • Ohmic junction
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SLIDE 5

Forming the junction

Evac EF EF Evac qφsem qχsem qφm

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SLIDE 6

Forming the junction

Evac EF qφms = qφm - qφsem EF Evac qφsem qχsem qφm

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SLIDE 7

Forming the junction

Evac qφsem qχsem EF qφms EF qφm Evac

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SLIDE 8

Forming the junction

EF qφm Evac EF qφms qφsem qχsem

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SLIDE 9

Forming the junction

EF qφm Evac EF qχsem qφsem qχsem

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SLIDE 10

Forming the junction

EF Evac EF qφm qχsem qφsem qχsem

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SLIDE 11

Forming the junction

EF Evac EF qφBn qφm qχsem qφsem qχsem

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SLIDE 12

qφBn

Forming the junction

EF Evac EF qφn qφm qχsem qφsem qχsem

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SLIDE 13

qφBn

Forming the junction

EF Evac EF qφn qφms = qVbi = q(φBn - φn) qφm qχsem qφsem qχsem

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SLIDE 14

qφBn

Forming the junction

EF Evac EF qφn qφms = qVbi = q(φBn - φn) xd qφm qχsem qφsem qχsem

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SLIDE 15

xd ρ

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SLIDE 16

qNd xd ρ

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SLIDE 17

qNd xd ρ

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SLIDE 18

qNd xd ρ

Poisson equation

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SLIDE 19

qNd xd

Gauss’s law

ρ

Poisson equation

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SLIDE 20

qNd xd F ρ

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SLIDE 21

qNd xd F Φ ρ

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SLIDE 22

qφBn

Forming the junction

EF Evac qφn qφms = qVbi = q(φBn - φn) xd qφm qχsem qφsem qχsem Φ EF

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SLIDE 23

Depletion region width

qNd xd ρ

Poisson equation

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SLIDE 24

Depletion region width

qNd xd ρ

Poisson equation Depletion region width

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SLIDE 25

qφBn

Forming the junction

EF Evac EF qφn qφms = qVbi = e(φBn - φn) xd qφm qχsem qφsem qχsem

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SLIDE 26

Schottky junction under forward bias

EF qφm Evac qφsem qχsem EF q(Vbi - Va)

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SLIDE 27

qφBn

Schottky junction under forward bias

EF Evac EF qχsem qφm qφsem qχsem q(Vbi - Va)

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SLIDE 28

Schottky junction under forward bias

EF Evac EF qφBn qχsem qφm qφsem qχsem q(Vbi - Va)

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SLIDE 29

qφBn

Schottky junction under forward bias

EF Evac EF xd qχsem qφm qφsem qχsem q(Vbi - Va)

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SLIDE 30

qNd xd ρ

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SLIDE 31

qNd xd ρ

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SLIDE 32

Depletion region width

Poisson equation Depletion region width

qNd xd ρ

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SLIDE 33

qNd xd ρ F Φ

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Schottky junction under reverse bias

EF qφm Evac qφsem qχsem EF q(Vbi + VR)

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SLIDE 35

qφBn

Schottky junction under reverse bias

EF qφm Evac EF qχsem q(Vbi + VR) qφsem qχsem

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SLIDE 36

Schottky junction under reverse bias

EF Evac EF qφBn qφm qχsem q(Vbi + VR) qφsem qχsem

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SLIDE 37

qφBn

Schottky junction under reverse bias

EF Evac EF xd qφm qχsem q(Vbi + VR) qφsem qχsem

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SLIDE 38

In case φm is smaller than φsem

Evac EF qφsem qχsem EF qφm Evac

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SLIDE 39

In case φm is smaller than φsem

Evac EF EF Evac qφsem qχsem qφm

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SLIDE 40

In case φm is smaller than φsem

EF qφm Evac EF qφsem qχsem

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SLIDE 41

In case φm is smaller than φsem

EF qφm Evac EF qφsem qχsem qχsem

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SLIDE 42

In case φm is smaller than φsem

EF Evac EF qφm qφsem qχsem qχsem

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SLIDE 43

Conclusions

  • If work function n-type semiconductor is

smaller than metal work function a Schottky barrier is obtained

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Summary

  • If work function n-type semiconductor is

smaller than metal work function a Schottky barrier is obtained

  • If work function n-type semiconductor is larger

than metal work function an ohmic junction is

  • btained